Should elected Members of Parliament in Northern Ireland be able to sit and participate in the Dáil?

Yes, but no voting rights.

Without the context of how it would impact dail operations or constituents either side of the border, this is a difficult question to answer. If it's with a view to a united Ireland, then absolutely yes.

deffitly but only if republican citizens can vote for northern politicans and northern citezens vote for republican politicans or combined both northern and republican partys.

No, but a cross border committee should be established invoking representatives from both parliaments

I believe members of the northern parliament should be allowed confer and discuss polices with members of the dáil

no, but there should be a regular forum of discussion between both parliaments to ensure continued cooperation and peace between the two states

governmentally they arent a part of the same country, however if the county were to choose to relinquish a position in the united kingdom government then i dont see whu not