there some reason why supply doesnt radiate from an allies

[tkobo]

colony into a neighboring allied region ?

[Balthagor]

Have you got an example? Savegame even?

[tkobo]

as id like an answer,ill try and rephrase.....

Should supply be able to radiate from an allies colony into a neighboring ally ?

[Balthagor]

In principle, yes. I'm not sure if that's how it got implemented. Start the game as Thailand and use cheats to buy friendship with France, get alliance and see if Indo China supplies your northern areas if you want to test it.