Syncing different activity trackers to one account

i was using garmin connect but now have a non garmin watch. so want to sync strava to my account. when i do so i basically have a life map for garmin and a completely different map for strava. how do i keep the map data from garmin history with new roads from strava on same map moving forward?

It sounds like you logged in via two services instead of connecting an additional service to your existing account - that’s a feature in the Settings page.
If you share the link to both CityStrides profiles, I can merge them for you.