-A "Curriculum" component that allows us to define programs that can be used across groups (think a class)

-A "Groups" component that allows us to create meetings that may or may not involve a particular curriculum (think a section of a class)

-An "Add-Ons" component where we can define materials for a given curriculum (i.e., a workbook), and then when creating a group we can define whether the add-on(s) are available at all, and if so whether they are required or optional.

To accomplish this, I have created a form for curriculum, which includes a subform for adding add-ons. After a curriculum is created, one can create a group, and on the group form the user has the ability to select a curriculum. 

From there, a lookup on a subform of the group main form is populated to show only the participant materials for that curriculum. The user is given the ability to choose, using the subform, the add-ons they want to offer with the course, and a decision box is offered to allow them to define whether the add-on is required or not.

Finally, on the registration side, participants in the class complete their information on the main form and a subform for participants is offered so they can add additional participants to their registration. On the subform, there are two checkbox lookup fields: one for required add-ons and one for optional add-ons. Both lookups are filtered to only show the add-ons that were defined when creating the group, and up to this point everything is working beautifully. I'm running into two main problems, though:

1. I'd like to be able to create an On User Input action when the group is selected (on the participants subform) to automatically select all of the options that are populated when the group is selected. However, I'm getting an error that the field does not exist in the form.

2. I'd like to be able to calculate the total of all add-ons so the registrant can get a breakdown of their price. I'm probably just feeling the effects of staring at this for two days, but I can't seem to figure out how to call the price (which is originally defined in the subform on the curriculum main form).

Also, I am aware that this would be far easier if I just dynamically generated a picklist, but I'm trying to incorporate an inventory tracking mechanism for the add-ons.

TIA for any help that can be offered.