Oh. Apparently, in the british contermandered elections, only the parties who ran in first can run and only with their first candidate? Or Wikipedia is totally confused?
In Quebec, there is no rule like that. The Champlain by-election was having a couple of minor candidates (like the Christian Democracy Party) not running in the general election, but running in the by-election.
From what I understand, yes. The rules on deaths during an election were found to be seriously wanting in South Staffordshire, so when it happened again in Thirsk and Malton there was far less confusion.
If the ballot paper in Somewhereshire looks like this:
A. BOLTON (Labour)
C. DENVER (Lib Dem)
C. FARLAND (Cons)
B. HIGGINBOTTOM (Green)
T. SMITH (BNP)
And during the election campaign, the LibDem dies, the only party which can nominate a candidate is the LibDem. No other (additional) party can join the ballot, and the other candidates can be changed if necessary.