Adding to a winning position is a classic technique, and scalpers do it in small ways: a second entry after a pullback, or an add on a break of a minor high.
The risk is that the average entry gets worse and the stop on the whole position needs to move. Without care, a 1 lot winner with a 0.5 lot add turns into a larger loser if price reverses.
Costs also double, since each entry pays the spread. For tight targets, that can cancel the benefit.
A sensible approach defines the rules ahead: the maximum number of adds, the size of each, and where the combined stop sits. The add should only happen when the initial position is already in profit and the stop is at or beyond breakeven.
It is also worth testing whether adds improve results. Compare the journal for trades with and without adds. Often the gain is smaller than imagined, or the adds hurt on the losing trades.
Do add-ons improve results, or only make the wins feel bigger?