Easyfits are as close to being idiot proof as you can get!
We have a variety of AIOs, AI2s and pockets. Everyone - gps, childminder etc can get on with all of them, as long as they are ready to go (rise settings done and correct inserts in).
When we used fitteds as well, I made sure all fitteds were plain looking (fluffles/stretchy bamboo), so they knew that if they looked a bit fancy they wouldn't need a wrap, which seemed to avoid any 'to wrap or not to wrap' confusion. They all went for preferred ones - my mum love our WN AI2s, my husband would go with easyfits and my MIL likes Close Parent Pop Ins cos she likes the pretty pastel colours!
I can't believe your mum hadn't changed his nappy in all that time - I would be hopping mad
we had to tell my mum she was changing Moo to often (she wasn't sure how long cloth nappies will last and changed her every hour or so!). We say either after a poo or about every three hours (depending on naps/food).
Poor little sausage - was his bottom sore?