Question How can I do this?

You need a third table so that you can match multiple businesses to multiple contracts. You can then use portals to this "join table" to assign companies to a given contract record. Define a number field in this third table to record your dollar amounts.

If you called your third table, Company_Contract, your relationships would look like:

Companies::BusinessID = Company_Contract::BusinessID (Allow creation and deletion for Company_Contract)

Contracts::ContractID = Company_Contract::ContractID (Allow creation and deletion for Company_Contract)

Place a portal to Company_Contract on your Contracts layout, add the BusinessID field, the Company_Contract::Amount field, plus the fields from Companies (such as company name) that you need.

To assign a company to a contract, pull up its record, select the BusinessID number for the company and enter the dollar amount into the amount field.

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kilbot wrote:

On any given contract I have multiple business that perform work

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Is the opposite also true - i.e. can the same business perform work under more than one contract?

Here's a demo file: http://www.4shared.com/file/227551445/4e0f5194/Contracts_to_Companies.html