what about your daugher....( Ihre tochter) it can be possible it is seen that they simply use ihr to represent you without caapital i in ihr
In order to mean "your" the "Ihre" had to be capitalized. This is not optional.
No, "ihre Töchter" would be "their daughters" (parents' daughters) or "her daughters" (mother's daughters).
"I am your daughter" spoken to her mother or her father would be: "Ich bin deine Tochter", spoken to both parents: "Ich bin eure Tochter".
Vebally, this could be confusing eg with adoptive children. I am your daughter, or I am their daughter !
You are right: neighbours' son: "ihr Sohn", their car: "ihr Auto", their daughter: "ihre Tochter", their daughters: "ihre Töchter", their sons: "ihre Söhne", their cars: "ihre Autos". It could also be her son, her car, her daughter and so on. To our new neighbour I could say: "Herr Becker, Ihr (formal your) Sohn und Ihre Tochter kommen."
The interesting thing is that "I am her daughter" and "I am your daughter" sound the same (ihre or Ihre). So in real life this will have to be inferred from context(may be even that might not help to a third person, some other form of the pronoun "your" or "her" might have to be used to make things explicitly known).