
<PAGE>
 
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

                                SCHEDULE 14D-1
                               (Amendment No. 3)
                  Tender Offer Statement Pursuant to Section
                14(d)(1) of the Securities Exchange Act of 1934
                                      and
                                 SCHEDULE 13D
                   under the Securities Exchange Act of 1934
                               (Amendment No. 2)

                               FORUM GROUP, INC.
                           (Name of Subject Company)

                             FG ACQUISITION CORP.
                         MARRIOTT INTERNATIONAL, INC.
                                   (Bidders)

                        Common Stock, Without Par Value
                        (Title of Class of Securities)

                                   349841304
                                ---------------
                     (CUSIP Number of Class of Securities)

         Edward L. Bednarz, Esq.                         Copy to:
         FG Acquisition Corp.                   Jeffrey J. Rosen, Esq.
      Marriott International, Inc.                   O'Melveny & Myers
           10400 Fernwood Road               555 13th Street, N.W., Suite 500W
        Bethesda, Maryland 20817                Washington, D.C. 20004-1109
             (301) 380-9555                           (202) 383-5300
 (Name, Address and Telephone Number of
Person Authorized to Receive Notices and
  Communications on Behalf of Bidders)

                           February 20 and 21, 1996
                           ------------------------
        Date of Event(s) which require filing Statement on Schedule 13D

                           CALCULATION OF FILING FEE
--------------------------------------------------------------------------------
Transaction Valuation/1/: $305,194,175      Amount of Filing Fee/2/: $61,039
--------------------------------------------------------------------------------

/1/ For purposes of calculating the filing fee only. This calculation assumes
    the purchase of (i) all outstanding shares of Common Stock of Forum Group,
    Inc., (ii) all shares of Common Stock of Forum Group, Inc. issuable pursuant
    to Stock Options vested as of February 15, 1996, and (iii) all shares of
    Common Stock of Forum Group, Inc. issuable upon exercise of outstanding
    warrants (other than warrants which are to be cancelled pursuant to
    agreements with the holders thereof), in each case at $13.00 net per share
    in cash.

/2/ The amount of the filing fee, calculated in accordance with Rule 0-11(d) of
    the Securities Exchange Act of 1934, as amended, equals 1/50th of one
    percent of the aggregate value of cash offered by FG Acquisition Corp. for
    such shares.

[X] Check box if any part of the fee is offset as provided by Rule 0-11(a)(2)
    and identify the filing with which the offsetting fee was previously paid.
    Identify the previous filing by registration statement number, or the form
    or schedule and the date of its filing.

    Amount previously paid: $61,039   Filing Party: FG Acquisition Corp.
                                                    Marriott International, Inc.
    Form or 
    registration no.: Schedule 14D-1  Date Filed:   February 23, 1996

                        (Continued on following page(s))
                              (Page 1 of 10 pages)
<PAGE>
 
         This Amendment No. 3 to the Tender Offer Statement on Schedule 14D-1
    and Amendment No. 2 to Schedule 13D (together with the Schedule 14D-1, the
    "Schedule 14D-1") amends and supplements the Schedule 14D-1 of FG
    Acquisition Corp., an Indiana corporation (the "Purchaser") and a wholly
    owned indirect subsidiary of Marriott International, Inc., a Delaware
    corporation ("Parent"), in respect of the tender offer (the "Offer") by the
    Purchaser for all of the outstanding shares of Common Stock, without par
    value (the "Shares"), of Forum Group, Inc. (the "Company"). The Offer is
    being made pursuant to an Agreement and Plan of Merger dated as of February
    15, 1996 by and among the Company, the Purchaser and Parent. The Schedule
    14D-1 was initially filed with the Securities and Exchange Commission (the
    "Commission") on February 23, 1996, and the Schedule 13D was initially filed
    with the Commission on February 28, 1996. Capitalized terms not defined
    herein have the meanings assigned thereto in the Schedule 14D-1 and the
    Offer to Purchase, dated February 23, 1996, which is attached as Exhibit
    (a)(9) to the Schedule 14D-1.

         In connection with the foregoing, the Purchaser and Parent are hereby
    amending and supplementing the Schedule 14D-1 as follows:

    ITEM 7.  CONTRACTS, ARRANGEMENTS UNDERSTANDINGS OR 
             RELATIONSHIPS WITH RESPECT TO THE SUBJECT COMPANY'S 
             SECURITIES.

         Item 7 is hereby amended and supplemented by the addition of the
    following paragraph thereto:

         The Company, Purchaser and Parent have entered into a Limited Waiver
    and Extension dated as of March 12, 1996, providing that, among other
    things, the Purchaser may extend the Offer by one day in exchange for a
    waiver by the Purchaser and Parent of the condition to the Offer that the
    Company acquire all equity interests in Forum Retirement Communities II,
    L.P. and an agreement by the Purchaser and Parent under certain
    circumstances not to assert after March 21, 1996 that several other
    conditions to the Offer have not been satisfied. In addition, Purchaser and
    Parent have acknowledged that the condition to the Offer requiring entry of
    an order by the U.S. Bankruptcy Court has been satisfied. A press release
    relating to the foregoing is filed as Exhibit (a)(11) to the Schedule 14D-1
    and is incorporated herein by reference. A Limited Waiver and Extension
    relating to the foregoing is filed as Exhibit (c)(7) to the Schedule 14D-1
    and is also incorporated herein by reference.


    ITEM 10.  ADDITIONAL INFORMATION

         Item 10(f) is hereby amended and supplemented by the addition of the
    following paragraph thereto:

         On March 13, 1996, Purchaser announced that it will extend the Offer by
    one day.  Accordingly, the Offer, originally set to expire at 12:00 a.m.,
    New York City time, on Thursday, March 21, 1996, will now expire at 12:01
    a.m., New York City time, on Saturday, March 23, 1996.  A press release
    relating to the foregoing is filed as Exhibit (a)(11) to the Schedule 14D-1
    and is incorporated herein by reference.  A Limited Waiver and Extension
    relating to the foregoing is filed as Exhibit (c)(7) to the Schedule 14D-1
    and is also incorporated herein by reference.

                                       2
<PAGE>
 
    ITEM 11.  MATERIAL TO BE FILED AS EXHIBITS.

         Item 11 is hereby amended and supplemented by the addition of the
    following exhibits thereto:

      Exhibit (a)(11) Press Release issued by the Purchaser and Parent dated
                      March 13, 1996.
      Exhibit (c)(7)  Limited Waiver and Extension dated as of March 12, 1996 by
                      and among Marriott International, Inc., FG Acquisition
                      Corp. and Forum Group, Inc.

                                       3
<PAGE>
 
                                   SIGNATURE

      After due inquiry and to the best of my knowledge and belief, I certify
    that the information set forth in this statement is true, complete and
    correct.

    Dated: March 13, 1996         FG ACQUISITION CORP.
 
                                  By: /s/ Edward L. Bidnarz


                                  -----------------------------------
                                  Name:  Edward L. Bidnarz
                                  Title: Vice President

                                       4
<PAGE>
 
                                   SIGNATURE
                                        
      After due inquiry and to the best of my knowledge and belief, I certify
    that the information set forth in this statement is true, complete and
    correct.

    Dated: March 13, 1996         MARRIOTT INTERNATIONAL, INC.

                                  By: /s/ Joseph Ryan


                                  ------------------------------------
                                  Name:  Joseph Ryan
                                  Title: Executive Vice President

                                       5
<PAGE>
 
                                 EXHIBIT INDEX
                                        
<TABLE> 
<CAPTION> 
    EXHIBIT NO.        DESCRIPTION
    -----------        -----------
    <S>                <C> 
    Exhibit (a)(11)    Press Release issued by the Purchaser and Parent dated
                       March 13, 1996.
    Exhibit (c)(7)     Limited Waiver and Extension dated as of March 12, 1996 
                       by and among Marriott International, Inc., FG Acquisition
                       Corp. and Forum Group, Inc.
</TABLE> 

                                       6
