question about tap on mouse while my other finger is on the mouse

Hello! Please can u help me. I made option when u can tap on mouse (not click). The problem is that the mouse no longer distinguishes between touching if my second finger is already on the surface of the mouse. but keeping the middle finger raised is uncomfortable! is there an option with which the mouse can recognize the touch of the left part if the right one already has a finger? Thank you! I will be happy with any help.