Your question is Cross-System Record Deduplication Strategy. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
You're combining records from multiple source systems into a shared data pipeline, and the same real-world entity can appear in different forms across those inputs. Some systems have partial overlap, inconsistent field quality, and no common primary key.
What strategies do you use to deduplicate records when there is no unique identifier across different source systems?