with the puppies being less than 2 weeks, just put the whelping box inside the pen, the babies should not be mobile enogh to get out of the whelping box, make sure mama is confortable in there, put a nice blanket in a corner so she can lay to get a rest from lactating the babies, mama's tend to stay very close to their young. and like I said plenty of wate and food and she will be fine.
