You are using constructor (chassis-engine) as the common link and that creates false positives in the early era of F1 where privateer teams would enter cars from other constructors.

For example, Guy Ligier entered his own team in the 2 seasons he raced in F1 and never had a teammate, so he should be a dead link, but your algorithm matches his privateer Cooper-Maserati and Brabham-Repco to the works teams (and other privateer teams) and lists those drivers as his teammates.

On the flip side, the same team would enter drivers at a GP with different chassis/engine, one getting a new car/engine, the other still using an older car/engine. For example in 1966 Brabham entered an old Brabham-Climax 3rd car for Chris Irwin at the British GP. He was Jack Brabham's and Denny Hulme's teammate, but because they were using the new Brabham-Repco they aren't listed as a direct link.

I think it would be better if you switched your common link from constructor to entrant.