Spend more quality time with your child. A real, honest-to-goodness quality time is not just about being with your child physically.
Rather, it is time spent sharing stories, experiences, and activities that will leave lasting impact.
Observe or ask what it is about yaya that makes her want to be with her more than with you. Perhaps yaya is more lenient or indulges her whims more, spends more time with her, or maybe she seems to be more appreciative and less critical of her behavior.
If your child feels that you are genuinely interested in her activities, thoughts, feelings, and interests, you shouldn’t worry about yaya taking over your role as parent.