First, Golden, you cant sell to your same brokerage account or they will get pissed and call you. I found that out, lol.
Since I keep little money available and Vanguard allows me to put bids in without upfront cash and lets me “borrow” their money until market close, I have to make a decision. Bring in more cash or sell something. After I free up the cash in another account, I just simply had the buy order and sell order teed up from both brokerages and set sell price just above current bid. I hit sell and them immediately hit buy for same amount and price a split second after. I have to do this only when I want to keep those shares and am wanting to sell something else to cover my funds for purchase.