Need to trigger OM Extension upon Bill-account selection or Order Type selection

Summary:

An Order Management Extension is created to check the Contract with the same Bill To Account of customer and update the currency based on contract currency. But now the OM extension is getting triggered only while saving or at the start/end of submission request but not while selecting the bill to account or order type like Pretransformation rule.

Please advise on the same

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):