All overworld Nether portals lead to the one same Nether spawn portal

Seed 8288000663050969136

Set up our first Nether Portal  at Coordinates -933, 64, 1481

Nether Spawn -100, 49, 182

So far, so good.

Go back to the Overworld and exit newly generated portal at -805, 64, 1450

Tried to make another Overworld portal at -559, 111, 908 to get another entry into the Nether, but went to -100, 49, 182 and returned to Overworld through portal -805, 64,1450. Even if we deactivate said portal.

Seed started on my son's PC (same environment Windows 11, Bedrock), passed to my laptop vis USB and then uploaded to the Realm from there. A character was lost, we had to unlist my son to the Realm and reinvite him back into the Realm. I know this last paragraph has no bearing on the problem at hand, but I felt full disclosure was best.

Thank you.