If you have existing data that needs to be imported into SPP we can absolutely help with that.
For Stripe data you can use our Stripe importer. It will help you pull in selected customers and subscriptions from Stripe without disrupting your existing setup.
For other client data, you can use the CSV importer available within your SPP workspace. Navigate to Dashboard → Services/Clients → [ ⋮ ] on the top right → Import and follow the on-screen instructions from there: