[TowerTalk] Two Verticals one radial field

[N4PT]

I think I have seen this discussed before but could not find it in the archives.

I have an 1/4 wave 80 Meter vertical with about 100 radials under it. I would like to use an old Hustler 4BTV for the lower bands. Can I use the same radial field for the 4BTV? I would only use one antenna at a time. 

1. What separation between the two vertical elements?
2. How to connect to the radial field ? A line back to the central point or just connect to the nearest radial ?
3. When using one vertical should the other vertical be grounded or open ?

73,
Art N4PT