I usually buy factor 30 and 50 for me and DH, and a separate child factor 50 for the dcs. It's the same make but ours is the great clear spray which is so easy to rub in and get even coverage, whereas the dcs is a cream spray which is not so easy, takes ages to rub in etc.
Is there any reason we can't just use our factor 50 on them? (Just musing this before getting up as I'm going out to buy some after school run, otherwise I'd check the bottles if we had any!) dcs are 9,7 and 18 mo.