Lay Offset falls below minimum SP liability

[gizzard]

I want to place Back bets with a Lay offset that may become an SP bet if the Lay isn't taken prior to the event going in-play.

Sometimes the liability of the offset bet falls below the 10 pound liability that BF insist on (or, the outrageous A$30 liability we have to put up with in Australia - nearly 20 pounds).

An example might be where a Back bet is placed at odds of 2.0 for a stake of 10 pounds and an offset Lay bet is triggered for odds at, say, 1.90 at SP after the odds fall. The liability of this Lay bet is now only 9 pounds so the offset bet is cancelled when the event goes in-play.

Is there a trigger that I can use for the offset for when it goes in-play so that there is a minimum liability?

I know that LAYSP can be used as a stand-alone bet but I would like to use a modifier of the original Back bet.

I'm doubting that this is possible as the stake isn't normally part of the trigger.

Also, I think there's a timing risk in any case. If the original back bet is placed just before the event goes in-play then there may not be time for the offset lay bet to be accepted before betting closes (the same if a separate LAYSP bet is placed). Am I right?