With arrival of Rules, one should be able to configure that with multiple projects. The possible howto would be:
- Different sets of “additional” custom fields should be added to defferent “additive” projects to be added to task in question to extend its fieldset.
- Primary project should gain Control “dropdown” custom field that would control which “additive” project to add.
- It would be necessary to setup several rules that would add one of the “additive” projects upon selection of corresponding values of Control “dropdown” field. Asana Business would be necessary for such rules though.
The issue with this approach would be that if one is “playing” with Control field, then task would gain multiple “additive” projects, thus gaining mix of additional fields.