Your help is precious Tatka. However I still have a question here. Do you mean, Taťka, that the wordorder "To je" (That is..) is more used when dům is not used but only intended in the conversation, while Je to (That is..) should generally mention the noun/nominative subject? In other words, we say Je to dům mojí babičky >> That is my grandma's house. But, To je mojí babičky >> That's my grandma's (meaning to say "That's my grandma's HOUSE")?
For me It is very hard to explain this in foreign language. Yes, to the question "Čí je ten dům?" Whose is that house? I can use a short answer "Je mojí babičky." or better "Mojí babičky." The sentence "To je mojí babičky" I would use in a full czech formal answer but we often use the shorter answer.