Ok, say you want to buy 1 contract, and then if price goes +5 you want to buy one more contract, then if price goes +5 you want to close the entire order. BUT, if price goes against you 5 before the second order fills, you want to close the entire order. AND, if price goes +5, and then +2, so not the entire 5, but then drops 7 back to the original price, you want to close the entire order.
sounds like a multi level OCA order using , stops and limits based on offsets, but giving the number of parts, a conditional order would be pretty hard using a standard UI. API could do it easily. But the API is not " easy". It is not hard either if you can code. That being said, if one were to do it in the API, it will probably be more flexible than described.
You need a program that continually monitors the involved positions and orders, and acts accordingly... Ie. algo trading.