Preschooler keeps clenching her jaw

As the title says, my 4 year old has been clenching her jaw a lot in the past few months. I think it started as stress and has now developed into a habit.

As for the cause of her stress, we've had some major life changes in the past few months. Her grandparents and cousin came to stay with us from the other side of the world for about 6 weeks and went back about a month ago. We also welcomed her new baby sister 2 months ago. She had been an only child before then.

I've been doing all I can to spend time with her and maintain our relationship while juggling the exhaustion that comes from a new baby, but it seems like she needs more. Her father, my mother, and my best friend who is practically a surrogate mother to her have stepped in a lot to help, but the jaw clenching remains.

So my question to other parents of multiples is how to help her adjust. Any tips or advice would be welcome.