Changing lot size after trade is entered?

Is it possible in metatrader to change the lot size after a trade has been entered either manually or through an EA? If so, how?

As I know it is impossible, the only solution is to close the trade and open another.

You can close any fraction of an open trade

Eg Buy 1 lot

Later ....Sell 0.5 lots
Later Still ... Sell 0.25 lots
Finally ... Sell 0.25 lots

As for adding more lots to an open trade ... NO ... Thats called 'opening a new trade'

In case anyone come.... yes you can. Click on the trade in your Trade Explore and then click on modify. Change it to Market order. Now however amount you want to shave off you do. Only thing is it has to be in whole. .01 pip increments. No percentiles. Unless your broker has Microlots.