I have a home with a 100 amp service. I am approved for up to 200 amp. I don't want to replace the old panel I just want to add a new 100 amp panel next to the old one. Off of it I want to run a subpanel of 100 amps to a shop. Is that Bad practice, do I just need to replace the original 100 amp panel with a new 200 amp and run a subpanel off that? I just don't want to spend the time rewiring a new 200 amp panel but don't know if I am just thinking in the wrong direction.