What is a Household?
Households allow individual contacts to be grouped as a single entity.
How do I attach more members to a household?
When a Contact is created, the Household record is created as well. Once that Household record is created in Salesforce, it should be available to be "looked up" using a Lookup mapping in FormAssembly.
For that lookup to work however, you have to know the value of a unique key in the Household record.
In most cases, it is safe to assume the Household name will be unique between all Households, and is generated in some fashion based off the Contact record. In general, the Household name will be equal to the last name of the contact, followed by "Household."
If this is true for your configuration, you can map a Lookup for the Household before the child Contact record mappings, then use that lookup in the child mappings.
Note that you'll need to add the mapping Households get value from lookup above to every child record that should be associated with the household.
You will need to set up a step between the parent object and child object that does a look up of the household. In the example below, I have set the connector to look up the household with the household email.
If you want to use the contact's last name for the lookup, and your Salesforce Nonprofit Starter Pack is configured to create Households in the default manner of adding on "Household" to the end of the last name, then you can use a lookup with a formula like this:
Where %%tfa_2%% is the field that you ask for your user's last name.
Then when you have the child objects below this step in the connector, you can use this lookup so they are all in the same household.