It's arrived!!!!! One more piece in the puzzle

Pura's mum's name was Julia Trancho, and father Alexandro (spelt Alyandro on one cert for some reason)
I have the address here as 1 Jones Court, Castle Street, Dowlais, but not sure what use that is to me - as I pretty much know for certain now that the family came to Wales around 1907 - so thats the Census out

The definate info I have so far then is as follows:
Joseph Henry Thomas b 1907 at 10 Bank St Merthyr, mother Ellen Jane Thomas, father unknown. Died 1970 Coventry. Had a brother William, and half sister Lillian (both untraced) Joseph's family did not live at that address in 1901

Pura Trancho, b 1911 at 1 Jones Court, Castle St, Dowlais, mother Julia Trancho nee Montes, father Alexandro Trancho. Died 1989 Coventry. Pura's family did not live at that address in 1901

Her parents would have been born, and married in Spain.
Joseph lived at 7 Brewery St in 1934, and Pura at 3 Aaron Row, Dowlais (or thats what it looks like, can't find trace of it though) I don't think I can get any info about who else lived at both addresses can I?
So basically, I have my grandparents, and both maternal great grands, but only one paternal grand - oh and a huge headache!
Any ideas as to what my next step should be?