Night nappy for older child

Hey guys, thought I would pick your brains!

My sister's wee girl who is 4 years old is having an ongoing issue with wetting at night and my sister was wondering whether there was some alternative to sposies for her, taking into account she is now about 16kg (though she is of slim build) She would need something that is super absorbent as she is a heavy wetter.

Any suggestions?

when gabriel was four he was in a fuzzi bun (same as honey child virtually) with an insert and a flat... did him with no problems. i think one of the ladies on here used a happy heiny pocket for her four year old too...