Triplanetary was not part of the Lensman universe, but much of the repurposing was done in revising the original Lensman novels, especially Galactic Patrol. All references to Virgil Samms are interpolations. (The character Roderick Kinnison was originally named Hinkle.) There are also clear distinctions in the original Galactic Patrol from the original Triplanetary universe.
See for a list of changes in the first two; see also . A change in the original synopsis for Second Stage Lensmen (Astounding 11/41 p. 10, IIRC) which I haven’t added there yet said that the Boskonian conflict was in its early stages in the time of Galactic Patrol, which is inconsistent with the mere existence of First Lensman.

I agree with Gharlane that the original versions of the Lensman novels are far superior; I think that the ret-conning was a serious artistic mistake by Dr. Smith. E.g., even in the early novels (I haven’t gotten to Children of the Lens yet), the original role of the Arisians is much better aesthetically. Characters as omniscient as the ret-con version are artistically unmanageable, and an accurate Visualization of the Cosmic All eliminates drama.