Splitting one wire into multiple wires can be done in many ways, this video shows how to splice wires using an open barrel splice. Common applications are sensor ground wires & 5 volt reference branching out to multiple sensors, 12v power branching to injectors as well as many others.
You can find open barrel splices here:
https://mavenspeed.com/collections/b2t-engineering/products/splice-crimps
Red handled crimpers in video can be found by searching for " Delphi 12085271 "
IN THIS VIDEO:
1: Overview of open barrel splices
0:37
2: Select splice using selection Chart
1:38
3: Strip wires to correct length
3:25
4: Crimping tool
4:35
5: Splicing 1 wire into 2
5:30
6: Bonus Trick
9:37