L2B profit on selection

[Laugro1968]

Hi all,

Say I made a profit on a selection pre-race.
Can I automate an in play lay bet for a % of that profit amount on the same selection?
Example:
Say I have a £10 profit on a specific selection. Instead of greening it up, I wish to dob it in running (trying to double my profit before greening up). Say BSP is 4, I'd have to lay the selection for £20 at 2.
How can automation figure out the original profit on that selection, the lay odds and amount?

Thank you,
Laurent