If I opened 2 sub accounts, how will system calculate my margin and balance – as combined margin and balance or separately?
Separately for each of your sub accounts, which are the same independent trading accounts as all others, so our margin requirements are appied for each account, so having more money in one account will not save you from having a margin call on another if there is not enough usable margin there. To avoid such situation – please monitor your accounts constantly and transfer funds from one account to another.