Controlling which slot parked calls go to

I am running asterisk 1.8.

I have a client who is complaining because they do not like the order in which calls are parked. It is set to findslot => next. Initially it was findslot=> first, but they did not like that if someone was parked on 702 and no one was parked on 701 the next call would be sent to 701 and so it’s misleading who has been waiting the longest. (Sorry, this is worded very poorly.)

The new issue is that they don’t like that if no one is parked the next call parked could end up on a 707 line, or whatever one is next in the sequence.

Is it possible to use a findslot=>next only if someone is parked on the line and just default to findslot=> first if no one is parked?