If mom has finished cleaning pup and etc...you can try to get him to latch on while she is between pups..... If she starts moving around alot during the delivery of her next pup you may want to move the pup to a waiting box, but you'll need to have a heating pad or warm water bottle in with the pup.
Sounds like Mom is doing
all on her own!!!!
Take some breaths and relax and just stand by in case mom needs you, but it sounds like she has it handled and is doing great!