We don't have individual trees per se. If the profile is an orphan, you can adopt it, assuming you have access for the relevant time period. For example, to adopt a pre-1500 profile then you need pre-1500 certification. If the profile already has a manager, you can request to be added to the trusted list. Then you will receive notification of changes to the profile, or if someone comments on the profile, so you will have an opportunity to be alerted to potential relatives who are researching the same people.