You can absolutely use that work experience in your application. Given the more entrepreneurial and family business nature of this business you will just need to explain your involvement and experience a bit more than is typical for my more traditional employers. I would focus on conveying two thins in particular
1)Impact/ results
-Most important aspect of how schools will evaluate your work experience, so this should be super clear. Given this is a family business schools will have their antennas up to make sure you have a track record of driving result and impact
2)Interpersonal Skill Development
-MBA programs are all about leadership and teamwork, and they are laser focused on your experiences in this regard pre-matriculation, so you need to highlight your best experiences in this regard
So if you can materially showcase this while describing your work experience you should be in good shape