Placing Field BSP bets with % Tick offset

[Exfundmanager]

How do I select ALL horses to back at BSP in a race on BA but simultaneously select % Tick Offset , say at 80% of BSP taken, and green up automatically across the field when my selection(s) hit their lower price limit?

[Exfundmanager]

Actually, it's more than that! Say i have got on a horse at a BSP of 11 and I really want to leverage that back up to a pre-determined % offset, say equivalent to a 15/1 winner in play by automatically laying off my profit on that selection COMPLETELY at 1.66 and therefore hoping to profit solely from a horse going close to winning but failing. Is this possible across the board in a race?

[rourkem]

This looks like a tough one. I tried some combinations but nothing is working. I think this may not be a feature yet?