Question about the Rebase (siebel 20.8)

We have parallel development going on int_Aug, Int_Sep, we created int_sep before int_Aug got merged into MAIN, Now we rolled up int_Aug to MAIN, we want to rebase int_sep from MAIN, question is what happened to the BC or BS script which got modified in both the int workspaces will it overwite the script or merge the script ? we do see the conflicts on the BS and Bc during rebase. we see override option which basically overrides the code from MAIN to INT_SEP if we dont check override option will it merge the code?