Both players' respective countries - DR Congo and Nigeria - booked their places at the South Africa finals thanks to comfortable aggregate wins at the weekend.
"We spoke about it at the start of the season," Clarke told the WBA website.
"We knew we had the possibility of losing Youssouf if he decided to come out of international retirement, which he did. I'm not really sure about Peter. He hasn't been called up to a Nigeria squad since I've been here. I don't know what his position is.
"We discussed it and we think we have enough in the squad to cover any absences in January. If not, it's a good month for it because the transfer window is open again in January, and if you need to address the situation you can.
"Many things can change between now and January, but as things stand we're comfortable with the squad we've got."