Hello,
you can find my solution for a delegation manager for onboarding on github: https://github.com/holgern/delegationOnboardBot

• I added referrerAccount to the config, so that delegationAccount can be different from the dapp account
• delegationAccount sends out the transfers (so that only one active key is necessary)
• beneficiaryRemoval is only applied on posts and not on comments
• account activity is only checked for new activity (beginning from time when the bot is started)
• Owned HP is used for maxUserHP
• The hiveonboard API is used to initialize all referred accounts
• Active delegation is checked by database_api.list_vesting_delegations
• Active key is stored in the beem wallet
• If notifyUser is false, a user will never receive a transfer memo

Please let me know if something does not work or when changes are necessary. I will also prepare a post about this and publish it later today or tomorrow.