Dividing domestic hot water?

[352now]

Hi i live in a 4 story home we would really like to have separate hot water for the 2 bottom floors and the 2 top floors. there are 3 mains that go all the way up.
i thought maybe the way to do it is by adding a new line along each main for the bottom 2 floors and keeping current line for top 2?

 

[phishfood]

That might work, dependent on how the water system is piped.

Do you have a schematic for your water piping system?

 

[352now]

I do not have a schematic. i'm not an expert but (i'm living here many years) and it seems like the lines are pretty simple (just going straight up near each water location and from there smaller connections which would just be reconnected). also happens to be that a large area near each line (on each floor) can be accessed with hardly any damage to the walls/floors.
i guess if i know its possible then what would be ballpark figure for something like this?
thanks