Hi again Ritak - lovely to hear you're staying at Xaloc in September - and we have twins too! Have been bringing them to Mallorca since they were four months old with no problems.
The larger supermarkets do usually have a small section of organic produce but there often isn't a great selection. I'm sure some of the market stalls would be organic - have never asked, but often the stallholders are selling just what they themselves produce on their finca and in my experience, quite a few Mallorcans rely on traditional means of keeping insects etc at bay, rather than chemical ones. (Btw, there is a small, very young orchard at Xaloc with various fruit trees - if anything is on them in September, do help yourself - we don't spray them!)
There are loads of shops near the beach selling inflatables etc but these are quite expensive, I think, compared to the UK. The 'Chinese' shops would probably be cheaper and I believe there are also a couple of shops selling second-hand inflatables. You might find that previous
Villa Plus guests have left inflatables behind which you can inherit - certainly this has happened for us in previous years, when we had the benefit of a very nice (and expensive) dinghy, a dolphin etc. Not sure what their policy is on leaving items like this - they certainly have very strict health and safety requirements so possibly they have to remove everything?
You won't really need to bring anything with you from the UK for the babies as everything is available locally. Possibly baby cutlery/feeder cups/dishes if you don't want to buy them? We used Pampers nappies, which are sold in Spain as Dodots. I seem to remember that we found it incredibly hard to find nappy sacks... they just didn't seem to be available, but this may have changed. I also used to take a small selection of items like Sudocrem and Calpol - although these are all available in Mallorcan pharmacies under different names.
One thing we found helpful was to take two individual buggies rather than our usual twin one - we bought a couple of cheap Mclaren pushchairs (the cheapest we could find!) and these lasted for years and stood up well to
flights etc. Our twin buggy took up so much space in the boot of the car - we wouldn't have fitted it in as well as all our luggage. Having two buggies also seemed to make life easier in restaurants where the tables were close together.
The lovely thing about Mallorca is that everyone is really relaxed in restaurants etc about the prospect of twin one-year-olds yelling in unison/knocking things over/making a mess! Spanish families seem always to take their children with them in the evening, even to quite 'posh' restaurants - I never felt we had outstayed our welcome anywhere!