Adding a radiator at this tee - bad practice?

[LiGhTfasT]

Not sure why but I had a feeling that adding a radiator return to this old drain off/isolator valve was a bad idea but now i've drawn it out it looks like the same situation as the radiator above.

Does this setup cause any issues? in my mind the water has 2 flows hitting head on? larger pipe is 3/4.

 

[LiGhTfasT]

Any ideas? i'm hoping to do this soon but a little worried adding a new rad from there will cause flow issues?

 

[ServiceNumpty]

Can't see for squiggly blue lines. Are there 2 pipes or just 1 pipe that loops back on itself.

 

[Bodd]

Are they 15 mm teeing off 22mm?