Need to write PO Line Number as a Condition in BPM Rules

Summary:

I have a requirement where business will be creating multiple lines with different PO categories which comes under Destination Type as Expense.

Here the ask is to Restrict the workflow approvals to PO LINE NUMBER 1. Since each categories has different approval limits hence have written rules as per the need. now 2 rules get fired since PO has 2 different categories in each lines.

I don't see any options for PO LINE NUMBER in the conditions search.

Is there any way to achieve this requirement.

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