Minnesota and Oregon did exactly what your parent is suggesting.
https://en.wikipedia.org/wiki/Metropolitan_Council
The seven counties in the Council's Twin Cities Metropolitan Area are Anoka, Carver, Dakota, Hennepin, Ramsey, Scott, and Washington counties. The Metropolitan Council or Met Council is the regional governmental agency and metropolitan planning organization in Minnesota serving the Twin Cities seven-county metropolitan area. The Met Council is granted regional authority powers in state statutes by the Minnesota Legislature. These powers can supersede decisions and actions of local governments. The legislature entrusts the Council to maintain public services and oversee growth of the state's largest metro area. This agency is similar to Metro in Portland, Oregon in that both agencies administer an urban growth boundary.
https://en.wikipedia.org/wiki/Metro_(Oregon_regional_governm...
Metro serves 25 cities in Clackamas, Multnomah, and Washington counties (as well as unincorporated parts of those counties.) Metro is the regional government for the Oregon portion of the Portland metropolitan area. It is the only directly elected regional government and metropolitan planning organization in the United States. Metro is responsible for managing the Portland region's solid waste system, coordinating the growth of the cities in the region, managing a regional parks and natural areas system, and overseeing the Oregon Zoo, Oregon Convention Center, Portland's Centers for the Arts, and the Portland Expo Center.