How can Secondary ledger hold information sent by subledger without passing through primary?

Summary:

We want to keep track of immobilization coming from asset and other manual adjustment separately then the primary ledger. Our first thought was "Adjustment Only" conversion. However, this conversion level prevents us from connecting an asset book to secondary ledger. We can't do subledger conversion neither, because it would create an entry in both primary and secondary.

Now we were thinking of doing another primary ledger, but we have to assign a Legal Entity to it and all of them were already use by the other primary ledger.

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