I have a mailing list which can be signed up to from more than one form.
One of these forms has custom data (address, postcode etc.), the other doesn't.
So, here's my problem. If a user signs up on form A (with custom fields), and then subsequently signs up using form B (with no custom field), all the custom data is deleted – presumably because the data in these fields in this request is empty.
My question is, how can I avoid this data from being deleted (i.e. can some data be persistent)?
I don't want to setup multiple lists, as this would cause lots of duplicate addresses, but this is the only option I can think of...
Other than setting up multiple lists, the only option I can think of is to use the API to check for existing subscribers and add the updated data.
In case you were wondering though, if you send a campaign to more than one list, any duplicates across those lists will be removed before the campaign is sent, so each address will only receive the it once.