I see. You need to identify who is the correct individual so you can link his descendants.
You can create the descendants' profiles and not link them to the father, if you need to create the profiles now. Then when you discover which is the correct father, you can link the profiles. If you do this, DO NOT create profiles as siblings (unless you have the correct mother identified and can link to her to create the sibling bond); if you create siblings without a parent to link them, they system automatically creates a father to link them.
However you choose to proceed, remember that errors are fairly easy to fix (as long as you have editing permissions for any related profiles). You don't need to worry about making a mistake - it can always be corrected!