Jones and Harriott able to face Wealdstone.
Loanees Jamie Jones and Callum Harriott are available for the tie at Wealdstone on Saturday afternoon.
Both parent clubs, Preston North End and Charlton Athletic, have given permission for the U's to use their players in the competition.
Speaking to the local press on Thursday lunchtime, boss Tony Humes said: "It's great that we have both of them available."
"We got permission from Preston North End for Jamie but with Callum, it was something that was done at the outset of the deal.
"When we first got him, we asked if we could play him in the cups we were in and they agreed so we're delighted to have him with us Saturday."