Where does 'Vuestro' come from?

Question

Aunque tengo una casa muy lujosa, prefiero la vuestra. I'm confused. Where does 'vuestro' come from? What happened to 'tuyo' and 'suyo'?

Answer

Hola Ricky,
"vuestro" is the possessive for "yours" in plural, so, it refers to people in plural. The possession is that of more than one person, as opposed to "yours" in singular "tuyo"/ "suyo". 
We have two different lessons for possessives. I imagine you've practised both. Here they are, just in case:
How to say mine, yours, his, hers, its, theirs
How to say ours and yours (plural)
Saludos
Inma