Lots of great feedback from the group and food for thought.
First, I would see what the parents purchase and use - and if they are bringing things with the baby and the things they typically won’t bring - you will have an idea ahead of time what to get.
You may find, when the baby is older, that the booster feeding and floor seat might be practical to have. But maybe the parents are used to having some things they bring on any trip with the baby. If a booster seat isn’t used at home, and they aren’t bringing a highchair, perhaps having an available highchair (may possibly have a friend to borrow from if a one-time thing or can find used). DD1’s youngest does use a highchair at home but gets by on trips w/o (typically in an adult’s lap), and the other two kids use a toddler chair at home (we had one passed down to them that DD1’s grandparents had made for her, and they purchased a 2nd from IKEA). In restaurants, we use the available booster chairs or highchair available.
When DD1/SIL’s first two kids were 14 months apart in age, they got a 2nd crib (both cribs can change into a toddler bed). They later got a pack-n-play and realized they really only needed one crib, so they gave away the 2nd crib/mattress. They have used the pack-n-play a lot and are glad they have it. They have used a regular playpen at home at one time with the older kids but have pretty much instead used the pack-n-play once that was purchased.
The parents get familiar with what they have seen their friends use with babies/kids.
When DD1/SIL/family lived 100 miles from us, it was always better for us to have the family time at their baby-proof place where all the kids’ essentials were. They did come to our city from time-to-time for a big day of something special in our city with us and then go back with the kids settled for the drive back. I set the boundary - often they really came to see some friends and I didn’t need to be a free hotel and fill-in around their other plans. They stayed with a very hospitable friend in her guest house off her pool - and she drew the line for having DD’s other friend ‘come over’. DD’s friend and husband later had a baby - with babyproof house and guest room so they stayed there - and they are the ones they wanted to spend time with – we did a meal together with them before they went over to the friend’s home.
DD1/family have traveled by car and by airline and brought her pack-n-play for the baby to sleep in, as well as some kind of stroller and the car seats. She has gotten better strollers along the way - one that holds multiple kids but is sturdy single width, and most recently a sturdy stroller for just the last child – she has five children, with the youngest kids age 1, 3 and turning 5 at the end of the month. This last airline trip (for a specific family event), she brought the youngest and the oldest (her H stayed home with the other 3) and the baby could fly for free on her mom’s lap. She had purchased the heavy sized properly sized bags to check the stroller, the pack-n-play, along with the older child’s car booster seat and the baby’s car seat (those two fit in one bag).
Along the way, I have dug out the wooden toys and all the toys/books. Baby blankets/baby quilts. Saved baby clothing gently used was gone through at the start. Eventually DD1 did go through gently worn older girl clothes because she had 3 daughters (DD1 and DD2 were 25 months apart in age, and had some nicer things barely worn). What didn’t get passed to her went to charity.
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