Window upgrade in 10 unit townhouse community

Has anyone gone through deciding how to go about updating the windows if the complex is old but windows are responsibility of the owners? Did you allow owners to upgrade on their own time and how was it to justify that?

I'm on the board and trying to ask to develop guidelines for window replacements as my windows leak, don't close, and the seals are all broken and we are working on a bigger project to replace sections of siding. However, there is one board member that insists that everyone needs to change their windows at the same time (and everyone listens to him by default) and wants me to measure everyone's window to get everyone the cost they would need to pay. This is totally unreasonable to me. They could not get past allowing individuals to upgrade windows so I was not even able to present window options I researched.

Our building is coming up on 50 yo and the building is not well maintained so it's frustrating to me how there is such high standards for uniformity yet at the same time using that has a reason to not maintain the building (because it's too expensive and they don't want to do it in phases because then it wouldn't look uniform between phases)