I feel like a moderator on this board, I can't tear myself away.
Anyhow, they will use it if you supply it. Just make sure it is in the bag with a note.
On a seperate note: If you are buying dreft because your baby has allergies to other detergents, I understand. If you are buying it because you have had people tell you to use it, I would try washing something for your baby in regular (normal) detergent. All specific baby detergents do is cost more, IMO.
I spent a lot of money on my first born who is now 4.5 buying seperate detergent, just because. When do you stop? You have to run a whole cycle of clothes just for baby, which isn't so bad, but I never had enough baby clothes to pile up before doing a load.
My 10mo old never had any baby detergent and does just fine.
Take cheerios and pure juice boxes for snacking. Introduce table foods so he/she can eat right from your plate. My 11.75 (now almost 9.5 mo's) mo old is going to be off the bottle and formula by the time we go. Right now we do a sippy at meal times. I will switch him to milk at 11 mo's. You can ask your dr about that one, if you like. I am not going to hassle with formula or bottles while there.