It would be hard to leave them for that long of a time frame. Why can't you see if you can find a doggie daycare in the area that you will be staying and just take them with you? You have time to investigate dog friendly places in the area and show it to your husband and mother in law, once she sees that the doggies can still be included then she might see that it wont spoil any fun,and maybe you can just take them with you after all. It's worth a try! one site to check out is called dogfriendly.com. also bringfido.com. I hope that this can help and be a possibility for you!
__________________  Brandy  and her love bugs Jeter  Axl  Yumi Yasha |