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If you are wanting a custom data filed field to be available for all your contacts then add it to your base participant types. Every database has a base participant type of "Individual" and "Company". If you add a custom data filed to the "Individual" participant type then users will be prompted to fill in the data field every time they create a new individual contact regardless of what other participant types it is assigned. If you enter the same custom data field under both "Individual" and "Company" then all contacts will be given the option.
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