If the person already has a profile in WikiTree, the best way to add your information here is to add it to the existing profile, manually. You should "skip" that person in your gedcom import.
Descendants of a skipped person will not be affected by your decision to "skip" the parent. Their profiles will be imported. However, after your import is complete, you will need to manually connect them to the family members who have existing profiles in Wikitree.