Since your IL's will have scooters, they and you will be loaded onto the bus first, so a seat will not be an issue. I read so many horror stories about traveling with a stroller(s) and DW and I have been taking at least one stroller for the last 6 years and except for the first couple of bus rides (learning a routine) it has not been a hassle at all. Biggest tip (for you and the people around you); always have your stroller folded and ready BEFORE you get to the front of the bus line. Our routine always goes like this, once we start getting into bus range, we empty the stroller(s) of the daily bags, fold it, DW takes l'il DD and a bag or two, I then take stroller(s) and remaining bags. Oldest DD, if sleeping has to wake up until on the bus. Once we get to the front if all seats are taken we stand off to the side and wait for an empty bus(rarely have ever had a long wait), DW and DD's will get a seat and I head straight to the back doors to stand with the stroller(s). I have just found it so much easier to stand with the stroller(s) then to try and sit and keep it out of the way. Enjoy your trip.