Please let me know if this sentence is correct as is; still learning. 金髪さんは私が彼女の友達だと思います
金髪さん could be both the topic or the subject; I'm confused in using both は and が in a sentence with two nouns mostly. I used は since its 金髪さん thoughts, and 私が because this is info i am conveying.
が marks the subject of a verb showing whats performing the action; and 金髪さん is the one performing the action of thinking. The sentence could be written 金髪さんが, depending on the context you could also be introducing new info, which would also be が. If that's the case what Particle would be used with 私. I'm Assuming が cant be used on both. 金髪さんが私_
Thanks, Clarifying 彼女 as she.