The system will tell you there is a conflict with ADR, but will let you choose FP+ overlaping with ADRs when you select them initially (A, B, C and Best Match options). If you want to change times after that, you will not get times as an option to choose until 2 hours after ADR. I get around that by having only one main person on ADR reservation with generic "guests" for other family members. I can change FP+ times for other family members to the ones I want (1 hour after ADR), and then copy those FP+ times to the person who is on ADR.