Oanda fxTrade, close position and open another in one order

Oanda FXTRADE platform. If I have a open long position and want to close it completely and immediately place a short position in opposite direction with one trade/one step sort of speaking. Stop and reverse I guess you would call it. Any ideas on how this could be done the fastest way possible and the least amount of steps.

If I would place a short order for double the amount of units than what is on the long trade would this close the long position completely and open the short for what is half of the amount of units of the short trade. Say 100,000 units were used in the long trade and I place a "pending order" for 200,000 units for a short trade. Than when price hits the "pending order" for the short trade it would completely close the long trade and open a short position for 100,000 units.

Or would there be a quicker, faster, least amount of steps to do this on the oanda fxtrade platform. Thanks Much

Open a opposite pending stop order at the same price than the SL of the position you want to close.

Yes to the above highlighted. Your long trade will close immediately and at the same time a short position will open.

I suggest you try experiment on your Demo acct platform with different units.

Thanks Much for the replies.

You are correct. If you open a position in the opposite direction for double the trade size...... it will close the original position and open a new position in the opposite direction.