Click the send icon on the lineup and choose the lineup group for that contest.
This is accomplished most easily by using the “One Group Per Contest” lineup group template, or otherwise making sure that the lineup group you’re sending it to only has one contest attached.
Every lineup card has a send icon next to the lock and trash icons (must be in full display view, not compact view). Click it and choose where the lineup goes: a group in the current build, a different build, a new build, or Favorites. To put a lineup into a specific contest, send it to that contest's lineup group.
Manually sending a lineup to a lineup group always locks that lineup into that group, so it won’t be replaced even if the Portfolio diversifier re-runs.