Yes, but...

You hit the cancel button and nothing happens initially but then you suddenly get a gut wrenching feel as something starts to expand inside you.

"Oh shit!" You say as panic sets in as the remains of your mom inside you start to transform back into her body inside you. In your panic to try and stop this you manage to accidentally hit the merge button again.

A strange feeling washes over you as the expansion inside you stops but you feel other parts of you start to grow, your chest expands into d-cup breasts, your hair grows out and your face softens. You then feel a pressure building in your crotch just below your dick as a slit forms. You then feel a shift inside your body as your uterus and vagina form fully. You feel something trying to push out of you and manage to get your jeans off as you orgasm shooting a pristine banana out of your pussy.

After recovering from your orgasm you figure out that you have managed to merge with your mom before she transformed fully back into herself. You somehow managed to put yourself as the primary merge target as you have her memories but you are in full control.