I am facing the same issue, When i copy & past the Overall schedule, & Chose the Base line to copy along with, but after copying i don’t find base line in copied overall schedule.
To counter this issues i made 11 Backup (Backup 01 ….Backup 11) & Overall schedule 01 to overall schedule 11)
overall schedule 1….(convert project Backup 1 as Base line)
Overall schedule 2 … (convert Project Backup 2 as base line)
But this like night mare…. Please help me