Ok First picture: normal situation

Second picture:
Back Bet

Like you can see, the last column shows the profit/loss situation. The potential loss is equal to the matched part of our bet, like you can see on column "Matched Stake". So, the Net cell just needs to read this last column. The Net cell or buttom with show 5£, we would click on it and we would be capable of making a fast Lay bet of 5£. Now, here's a question: Should the unmatched part of the bet be cancel or not? To make things simple, I think it should be cancel at the same time the Lay bet is made. But it would be great to make the net buttom a litle more inteligent, and when the Lay bet of 5£ is made and the last 5£ of the stake are filled the Net buttom would show again 5£. Here, you can't read the amount to Lay from the Profit/Loss column because at this time the first Lay Bet could have be filled already. To know the exact amount for the second Lay we have to ways: One is if we had the betting history on Excel like we have on BA; the second way would be to make some math but along with the beting history. At this point I'm a bit lost too.
Here its a Lay bet

Its the same idea as before. On the profit/loss column the part matched from the bet is the positive value of 8£. It can be read from the Matched column too.
I think a Net buttom is a precious thing. Maybe that's way its so dificult to explain and specially to make it work.
I hope with this information you develop a Net buttom. I will read a couple of things that might help you with this too.
Dedes.