Dollar General Corp. (DG) - Get Report on Friday extended its tender for Family Dollar Stores Inc. (FDO) until year's end and said it intends to file a proxy statement ahead of its target's special meeting to vote on a rival agreement to be acquired by Dollar Tree Inc. (DLTR) - Get Report .

Goodlettsville, Tenn.-based Dollar General said that as of Thursday about 4.1 million of Family Dollar's 114 million shares had been tendered and not withdrawn from its $80 per share offer. That offer would have expired at 5 p.m. on Friday if not for the extension.

Charlotte-based Family Dollar in July agreed to be acquired by Dollar Tree in a deal valued at $9.2 billion, or $74.50 per share. Dollar General submitted its rival offer on Aug. 18 but so far has been unable to scuttle the original deal despite pledges to divest upwards of 1,500 stores to calm regulatory concerns and pay a $500 million reverse breakup fee if the offer does not meet regulatory standards.

Dollar General in its statement extending its tender urged Family Dollar shareholders to vote against the Dollar Tree deal at a special meeting scheduled for Dec. 11. The aggressor said such a vote would send "a clear message to the Family Dollar board to promptly engage in discussions with Dollar General," noting that a rejection of the Dollar Tree offer would not obligate shareholders to support its rival offer.

The company said it "will continue to cooperate" with the Federal Trade Commission to seek antitrust clearance for a Family Dollar deal.

Family Dollar's reluctance to engage with Dollar General has some shareholders unsettled. Elliott Advisors (UK) Ltd., an affiliate of activist investor Elliott Management Corp., on Oct. 17 said it was nominating a slate of seven directors to the Family Dollar board.

Elliott, which holds about 4.9% of Family Dollar, in a letter said that it has launched the board battle to encourage directors to do everything in their power to provide Dollar General with a level playing field. The firm said that Family Dollar appears to have missed an opportunity to facilitate a bidding war between the two suitors.