How to make the Supplier Contact not auto populate when added to Negotiation

Summary:

How to make the Supplier Contact not auto populate when added to Negotiation

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When adding a supplier to a negotiation the supplier contact are auto populated. Is there a way not to auto populate this field and let the user populate it and just use the additional email function?

Reason is that there are business scenarios where we don't need to have Supplier Contact added and just use the additional email. As we don't want a negotiation sent to supplier.

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