Place a green position offset on net stake

[ringo.simpkins]

Hello, can some explain to me how or if this can be done. I am wanting to place some back bets, if i were only placing one i could use the offset by %age to green out at a certain percentage of the bets stake, eg a fiver back bet, off set at 10% would place the lay to give a 50p profit.

What I would like to do is place a few back bets, then at a certain time, off set the net stake, eg 3 back bets at a fiver eack would be fifteen quid, at x time place a lay with greening offset to 10% to yield £1.50 proft.

Is this possible, I cannot see an obvious way to do it in the drop downs. Thanks for any help