combine cellcontents based on comparison multiple cells

Hi,

I am really stuck on this.

My sheet is as follows:

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I would like to have all doubles removed and their unique accounts into one cell.
In this example John occurs twice with the same address, postal and country, so his account is combined. The 888 should not be combined as it is not the same John.

My result would look like:

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I hope anyone is able to help me, I have been trying in VBA but no luck so far.

Something like this scarm?

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