supplying 2 houses from 1 supply

[foxy123]

have a situation where doing a barn conversion and have been quoted 16 thousand to run new supply to barn.
main house next to barn has a 100 amp supply fuse ,pme system.
wondering is it legel to run new dwelling off that main fuse .(its going to be holiday let so owners will be paying both bills anyway )
eg. would connect tails probably into henry blocks then to original c/unit and to a isolater ?then onto new barn.
any ideas , thanks

[kbrownie]

You need a seperate suppy, who has quoted you and why so much?