switching from Tier-2 to Tier-1

[rupas9]

Hi,
Currently I'm in UK on Tier-2 (ICT) and further have 2 dependents on it, now i'm planning to get my Tier 1 visa but due to some problem with maintenance fund i'm currently applying for myself only, my Tier 2 visa is going to expire in august end, so in case I got my Tier 1 visa do my dependents who are on Tier 2 dependent visa can remain within UK till their visa get expires.
and do I need to go back to india and again come back to UK entering on Tier 1 visa, or my status of visa from Tier 2 to Tier 1 will be changed automatically.

Please help as I'm really worried, as i was thinking that after 1 month I'll apply for their visa as well as the maintenance fund will be available at that time. So do my dependents can still live in UK?