Calculate the time to leave the last activity
For a 5:00 handoff, allow thirty minutes to drive, ten minutes to park and walk to the door, and ten minutes for an ordinary delay. The car needs to leave by 4:10. If the group is still a ten-minute walk from the car, leave the activity by 4:00.
Identify the optional part before anyone buys a ticket
A shop visit, dessert stop, or second exhibition may be easy to remove. A ticketed activity ending at 4:15 cannot coexist with the sample return unless the group has another transport plan. Explain the constraint before booking so nobody feels pushed out of an activity halfway through it.
Protect the return when the group splits
Choose one thing to skip if the visit runs long. If the group splits, name who returns with the person who has the deadline. Do not let the only driver discover the hard return time halfway through the visit.
One adult may want to stay for the second exhibition while another needs to leave. Check who has keys, tickets, car seats or other shared equipment needed for each route. Give the returning group a confirmed departure time and meeting place. A spare hour on paper does not help if the only driver is still inside.