Hi @cullen_wilcox. Are you talking about adding UserParameters to an iLogic Form here? In order to be able to add a Parameter into an iLogic Form, you should mark each of those Parameters as 'Key' within the Parameters dialog. There is a column in that dialog labeled Key, with a CheckBox for each Parameter row. Also, once you have added a Parameter into an iLogic Form, if you then change something about that Parameter within the Parameters dialog box, such as changing its name, changing if it is Multi-Value or not, or something else major like that, then you will need to remove that Parameter from the iLogic Form, then add it back in again, before you will see those changes available in the iLogic Form.
Also, in the Parameter dialog box, there is a column labeled 'Export Parameter', with a CheckBox for each Parameter. If you add a Check in that CheckBox for a Parameter, that does multiple things. It will then be included when you derive or link the parameters of this model into another model. But it will also automatically create a 'custom' iProperty, with the same exact name, and same exact value as that Parameter, and that custom iProperty will automatically stay up to date when that Parameter changes. But that Parameter will not change due to changing the custom iProperty. However, no iProperty can have a multi-value list. So, the custom iProperty will only have the current value of that Parameter, and its other possible values will not be available to that iProperty. So, if you added the custom iProperty into your iLogic Form, instead of the UserParameter, you will not have the multi-value list available in the iLogic Form.
Wesley Crihfield

(Not an Autodesk Employee)