(note: this is all from memory)
I remember my own sleepovers. I was 7, because of my small size I looked about 3 or 4, this was after I was back in diapers. now this was a 2 week stay because it was a bit of a busy time of the year for my parents, it was with my friend, he was actually a year older then me, but he was just slightly taller then me also. now he had a bit of an issue, he was always wetting himself, from what I remember he had a lot of difficulty when holding it, and he never made it to the toilet. he was the only other kid I knew who was still in diapers, at this stage I was nose high to him. his older brother does after school wrestling classes, neither me or my friend really understood why he liked it, he was older then my friend by just a year or so, but he was also pretty small also, i'd say my friend was about the height of a 5 or 6 year old while his brother was about as tall as a 7 or 8 year old. weak bladders were hereditary in their family, my friend's older brother wore pull-ups because he only had an accident 50% of the time.
anyway my all 3 of us were in just our diapers and pull-up and in the yard, it was pretty hot being the summer and everything. I was wearing a super hero cape, it was either a superman or batman cape, I don't remember, my friend was more into the knights and stuff and had a toy armour set.
lunch came about soon after we all had ham and cheese sandwiches which were awesome, and my friend's mother brought us all baby bottles full of milk, when I questioned her about it she simply told us all we were to drink from bottles until we all potty-trained and stopped wetting and messing ourselves, we then ended up in the loungeroom just after lunch because my friend had an old Sega console and had some great games, well great for the time, like sonic and others. we ended up after that watching TV for an extra hour. there was no AC to cool down the house but my friend and his family did have was a pool.
ok so after a bit we ended up getting ready for a swim. my friend's mother entered the room and my friend's older brother asked about going for a swim and we all got changed into swim diapers, and were in the pool faster then we could even say swim time. the pool time was fun even if I had to sit in this little kids water swim ring seat designed for kids around 3-6 years old, we splashed about and had fun except the point I pooped myself during the swim. my friend also pooped himself while swimming just a little later, he always was using his diapers to poop because he was already wearing them and he figured he might as well use it since he was wearing it anyway.
now the night came about, and we had to bath thoroughly because of all the pool water, my friend's mother said something at the time I thought was real, "better wash the pool water off and wash your hair, or the pool water will turn your hair green" she told us and so we washed, but she then ended up taking over washing each of us as if we were toddlers. after a bath we had dinner which was McDonalds or I think it was at least. again with our food we had to have milk from baby bottles again, we played for a bit but then we had to go to bed, we all had our diapers changed, at this point my diaper was soaked and dressed for bed, I was dressed in a onesie that was originally made for older kids in diapers from a special needs specialty store but it looked just like ones for babies. we got our teeth done and led into the bedroom. both my friend and his brother had cribs, actual cribs, their mother made them since she was good with carpentry and such and we all climbed in and the sides were closed. me and my friend tried to stay up as long as possible and chat, but his brother then started telling us to be quiet, we did end up falling asleep soon after.
(Side note: now that I apply hindsight to this sleep over day, I think it may be one of the pebbles that resulted in me being an ABDL later in life thanks to it sparking an interest in baby items as a kid)