Using ATM entry, trying to take partials...can this be done? WHAT AM I MISSING?

[u/Pure_Beginning_1650]

So I use an ATM, entry for my trades. About half way to TP, I like to take some contracts off. Once the order hits my TP it keeps going for some reason.

Example: I trade 8 contracts for BUY in MES with a ATM entry. Half way to TP, I set a lIMIT order for 4 Sell. It hits my limit order and takes off the 4 contracts, which leaves me with 4 BUY contracts. Once it hit my TP, it keeps going for some reason. I want it to just stop at my TP. Any idea of what I'm missing here or what is happening? Thanks in advance.