I seem to recall that they will only give data to direct decendants.
As for the census, I have not come across one for Switzerland. I don't know if they do one, or whether they never publish it. Swissgill: can you comment?
They quote two children by name, but at 1911 there was one deceased child and one living; Enda aged 3 b Sandown IOW, presumably the Edelweiss Mildred E Hirter b 1908 in the BMD indeces. The other two are Vera N b1910 and Karl L b1911. Not quite sure who the two are that the registry state, unless I've got the wrong end of the stick!
Paul