「だ」はいつか「が」のようにつかいます？ || だ sometimes used as a が?
A couple of times I've heard だ being used mid-sentence, and this wasn't for things like connecting two sentences either like in the case of だから, it was more used in the context of "You won't take my sister away!" but the character at the time used a だ after "sister" when I was really expecting a が, or even an を, I can't remember the exact sentence. It's not the only time I've heard it like that either, although examples fail to come to mind.

Question

「だ」はいつか「が」のようにつかいます？ ||  だ sometimes used as a が?
A couple of times I've heard だ being used mid-sentence, and this wasn't for things like connecting two sentences either like in the case of だから, it was more used in the context of "You won't take my sister away!" but the character at the time used a だ after "sister" when I was really expecting a が, or even an を, I can't remember the exact sentence. It's not the only time I've heard it like that either, although examples fail to come to mind.

Answer

I know you said you can't think of any examples but I think we'll need some to solve this problem. I can't think of anything that would explain what you're hearing, at the moment, so I'd have to see it. The only things I can think of right now is either you misheard it or it was really two sentences like "(That's my) sister! You won't take (her) away!", in which a だ could easily go after sister.