Under proposals drawn up by Unite's regional committee in Scotland, union delegates will stay away from the Brighton event if the suspensions of two figures in the Falkirk row remain in place.
A Labour party source said the move was self-indulgent and damaging to leader Ed Miliband.
Labour and Unite are at loggerheads over how the union tried to secure the Falkirk candidacy for Karie Murphy. Unite recruited more than 100 members, but claims emerged some new members had not consented to joining the party.
Labour launched a probe into the claims and put the local party into special measures, while Ms Murphy and Stevie Deans - who was Unite chairman in both Scotland and in Falkirk West - were suspended.
The row prompted Mr Miliband to back radical changes to the party's historic link with the unions.
Unite in Scotland has written a draft motion offering full support to Ms Murphy and Mr Deans. The motion also called for non-attendance of conference by members if the suspensions remained in place.
Labour declined to comment.