Congrats on your wedding.
If it were my pets I would prefer they stayed at my house. If your caretaker is good with any animals she should be able to take care of your chinchillas and learn quickly when it comes to handling them. Of course it is important she knows how to fill and properly assemble the waterer and ensure there is a constant supply of food. It may be a little extreme not changing the cage liner after 9 days for two chins but she should only have to change it once during that time. They shouldn't have to be removed from the cage for play if she is not comfortable doing that. 9 days really isn't terrible.
Considering other people's bad experiences that I know of (promising to take care of the animals but not doing it) it might be best to have someone check the others' work to make sure it is getting done at least every 2-3 days, perhaps rotating if possible.
As far as mounting issues I don't know. I've seen my chinchillas go after each other and they are fine but I'm somewhat new to having multiple chins in the same cage. As I've said there is always a risk something can go wrong at any time and it should be carefully weighed.
The big disadvantage of moving them to a different place is that it will cause a lot of stress, and after 10 days they'll be used to the new place and it's going to stress them again moving them back. I think this is to be avoided if possible.
