Use the option of "merge and split" in the entrustment software, usually in "floor fund" or "LOF fund" or "exchange fund".
However, the interface of each broker is slightly different and needs to be solved by itself.
Divide and sell:
T-day subscription of parent fund (on-site subscription)
T+2 days (very few have T+ 1).
Before 3pm on T+2, select the option of "merger and split" and enter the parent fund code.
On T+3, you can see that the parent fund in the account disappears and becomes two sub-funds of Class A and Class B, and then you can sell it.
Purchase, merger and redemption
Buy a and b shares on t day
T+ 1 merged into the parent fund.
T+2 days redeemable