Nether Portal linking

Recently encountered an issue regarding Nether Portals linking up.
We have 3 people on the server with a Nether Portal each living at the following co-ordinates:
1) 0 / -1000
2) -700 / -520
3) 305 / -654

We're all, clearly, well away from each other. However, as soon as we enter our Nether Portals, we are all sent to the same portal in the Nether. When exiting the Nether, we're all sent to the 2nd co-ordinate.
(I know how Nether Portals work and this should not be happening).

Edit 2:
The whole idea that 1 block in the Overworld accounts for 8 blocks in the Nether was a design intended for traversing a large span of land quickly, but with risk of lava, Blaze, Ghast, Piglin, Hogs, Magma Cubes and Wither Skeletons.

If the current system is "working as intended", I think you need to rethink your intentions with the Nether system because this completely negates the original fun feature of travel in the Minecraft world.
Players who want to build thousands of blocks out in the Overworld, now have to still travel thousands of blocks out in the Overworld just to build a Nether Portal in the place it should be.**

Your Nether Portal system is flawed and contradicts its original function for a means of travel. Portals never used to function the way they do now. They would always create a new Nether Portal and THAT is what players wanted. It allowed them to travel and create networks of portals for the specific purpose of travelling to specific biomes, villages and houses.

What is the purpose for the Nether dimension to equal 8 blocks in the overworld?
Not for travel anymore apparently.