Importing data tree

Hello, I am having trouble keeping the data tree together for a multiple lookup box.

Here's the issue I'm having:

(In this scenario I have 3 fields)

Year,

Year 2000 has ID "YEAR2000"

Year 2001 has ID "YEAR2001"

Make,

Year 2000 has ID "YEAR2000", Make Suzuki has ID "YEAR2000SUZUKI"

Year 2001 has ID "YEAR2001", Make Suzuki has ID "YEAR2001SUZUKI"

Model, (on import)

Year 2000 has ID "YEAR2000", Make Suzuki has ID "YEAR2000SUZUKI", Model Wagon R+ has ID "*UNIQUE1*"

Year 2001 has ID "YEAR2001", Make Suzuki has ID "YEAR2000SUZUKI", Model Wagon R+ has ID "*UNIQUE2*"

The issue is in the bold. On import, The second column chooses the first available. Where it's supposed to choose Year 2001 has ID "YEAR2001", Make Suzuki has ID "YEAR2001SUZUKI", Model Wagon R+ has ID "*UNIQUE2*"

Hope this makes since and hopefully someone can give me some direction. What's odd, is it works fine when manually adding - but import loses it.