imported file -> trade out at specific price for 50%

I'm trying to green up at a pre determined price, but not sure how to do it.

I have an import file that looks like this:
"Bencic" 1.86 2.04

The first number is the open trade price.  The second number is the close trade price.

At the moment, when I open the trade, I will also place an unmatched bet at the close trade price.  Then when it is opened, I initiate a trade out to hedge profits.

So that's 3 trades.
1. Lay at 1.86 for full stake
2. Unmatched Back at 2.04 for half stake
3. Trade out to equalise profits

Ideally I'd like to do this in 2 trades.
1. Lay at 1.86 for full stake
2. Unmatched Back at 2.04 at a stake that would equalise profits

Is this possible?  Any help would be greatly appreciated.

Hi
The basic formula for the back amount to green up matched lay bet is: (bm_laya*bm_layp)/back_price

assuming the lay bet is matched, for the backing trigger amount:
(bm_laya*bm_layp)/imported_2
or
(bm_laya*imported_1)/imported_2

if you want to back regardless of lay being matched or not:
(full lay stake*imported_1)/imported_2

Thanks Mark.  I'll give this a go!!

It works! It's exactly what I wanted.  Thanks Mark.