You may be using Workspaces and Lead Partitions in Marketo, but here's a twist. If you are separating both Marketo Assets with Workspaces and Marketo Leads using Lead Partitions, you may also have a deduplicate rule in place (which we'll deal with in a separate blog) to allow fully separate leads with the same email address to exist in the different partitions. You might, for example have a line of business that targets individuals, and one that targets enterprises, and you want people to be able to exist in both.
In this case, you can have support alter the custom duplicate rule to be Email Address + Lead Partition so you can target the partitions with the API and with list uploads, but the question may come up about whether you need to apply this duplicate rule to form submissions.. after all, its not as if you want to have the partition ID in every form as a hidden field right?
Here's the scenario:
If you have a lead in Partition A with a particular email address, and then that same lead fills out Form B, which only exists in Workspace B, which only has access to Partition B, what happens is curious. Even though the form is in another partition, the lead in Partition A will be updated, which is no good. If however you simply apply the custom dedupe rule to forms, marketo knows enough to also submit the partition ID, and a duplicate lead is added to Partition B.
So, in short, in this situation you don't need to supply the partition ID in every form, but you do need to set the custom deduplicate rule to apply to forms.