Please don't shy away from requesting mobility assistance for the seniors, which ever airline they may be flying. Boarding, and deplaning, will be much easier for THEM and everyone around them. Perhaps do the same if you are flying with the small child. When you check in for your flight to SJU, make it a priority to request gate assistance at SJU. That information is sent with/on the passenger manifest to the arrival airport ( SJU). Mention to your cabin attendant inflight that you have requested " gate assistance" on arrival, you should not then be needing to " find' it on your own when you arrive.

Leave the surprises to chance, and the surprises will bite you when the chance presents.

Breeze