We use oms/rms system which is provided by TR(Thomson Reuters) and they are empaneled vendor with exchange which means their systems are tested rigorously and continuously audited. They provide the same version to all their member clients, so, adding or customising something has to be done on their system which in turn will be tested and approved by exchange.
Also if you are worried with front running in squaring off then it is same with every broker, any one can do according to you.
Front running is not easy thing to do, I recommend you to go deep into this, understand the prerequisites to do this, can’t be completed just like that, I mean in any case. One need to enter slowly with out effecting market price, most importantly considerable follow up quantity should be present, retail clients don’t have that much quantity which can move market prices.Generally If any big clients are there, they only take care of their positions without leaving the onus on RMS to act.
Other point, considering the volatility and gap opening, no one can give you exact point of square off and stick to it.
Personally I can only suggest you to take this out of your mind, but it is up to you.