Yo, Unfortunately this is not a matter of the best way. The rule that if a person is living, he/she is the only one who can enter his/her DNA information is required for WikiTree to be in compliance with the new international privacy laws put in place in 2018.
Your family members can join as guest members, enter their DNA information, make you a manager of their own profiles, and then never do anything more on WikiTree if they don't want to. That is the only way their DNA information can be posted here. When you are manager of their profiles, you can deal with everything else.