Good question, although there’s no real guarantee in terms of moving money to Betfair. You can look to target certain selections that you think will lose & then back and lay. Although you will want some knowledge on that sport to do so as it can obviously go the other way with winning more money with the bookmaker and losing money with Betfair.
The short answer is there’s no real guaranteed way to do it but that doesn’t mean you still can’t try.
Are you trying to minimise withdrawals with an account by moving it over to Betfair?
I know this answer doesn’t provide too much so let me know if you need any further help, cheers.