No offence, but it makes no sense whatsoever to repatriate 'Lady Edith' for static display only. Given the huge costs involved in getting her back there would need to be some means of generating revenue from her subsequently and static displays don't cut the ice in that regard.
If you're serious about getting Blennerville up and running again I would suggest that it would be better to take baby steps first and get what's currently available up and running first and then build on that if possible.
I do think though that if Blennerville is to survive then it needs to make a serious effort to create a proper heritage railway as distinct from the current fairground ride setup which is utterly devoid of atmosphere. It badly needs a makeover to create some atmosphere of the period when the T&DR was current. It needs things like platforms which don't look like they were transplanted from the DART system, appropriate station buildings, timber crossing gates rather than the current steel Bord na Mona ones, some form of relevant signalling (even if it's not operational to begin with), rolling stock which is made over to make some effort to look like T&DR (painting them in the appropriate colour would help), etc. All of this costs a small fortune of course, and don't for one second think I'm saying that it's a trivial matter, but I believe that the railway has no future if it is not developed along these lines.