Considering Margin for open poisition

Hi,
This is must required feature, as your terminal is not considering open positions while calculating margin requirement for new orders.

Say,
10 Lot of FUT Buy position is open.
We are sending 20 Lot Sell order to close 10 lot open position and add new Sell position of 10 Lot, but system want 20 lot margin in account to execute this order, while my 10 lot open position is already there, hence logically 10 lot margin must be available to execute this order.

Kindly correct this feature.