Dehydrated baby rabbit ?!?

my bunny had its second litter of kits and one is very small compared to the others. i read that u should pinch the skin on the back of their necks and if it stays tent or takes a while to go down it is severely dehydrated. i was looking on this site and someone said to take the mum and the kit out and let is suckle. we done that and it suckled but about 10 Min's later it looked normal again. what should we do and if will the mum still feed the other kits seeing as she just fed one ???