what would be a great addition is, if we could pass on the variable if a plan is "selected by default" onto the URL for the registration form.
here's the original url to display the rego form and all plans: index.php?option=com_comprofiler&task=pluginclass&plugin=cbpaidsubscriptions&do=displayplans

now if we could add the variable if this plan is selected by default like this:

index.php?option=com_comprofiler&task=pluginclass&plugin=cbpaidsubscriptions&do=displayplans&select1 or similar for plan with the id1

this would then make it possible to place links to certain pre-selected plans in the registration form that require a unique membership but are not child-plans or merchandise-plans.

in my scenario this will not work. please let me explain:
I have 3 plans that are exclusive (only 1 can be selected - and one is also set to default)
I have about 10 other plans which are almost like add-ons to the above plans, However, I cannot use them as child plans becuase all 3 exclusive plans need to be able to use them. As far as I understand, you can only have child plans for a single exclusive plan and the child plans cannot be shared between the exclusive plans. Now if I want to sell the optional (add-on) plans, I have to send clients to the registration page, which will display ALL of my plans. In there they will then have to make their choice of add-on plans.
This works ok, BUT it would be fantastic if we could pass on a variable in the URL that already pre-selects any add-on plan on the registration page that shows all plans.

This would allow us to set up an article in Joomla that shows say a table with all the optional add-on plans as links. Then when people click on one link, it would automatically be pre-selected on the registration page.

I cannot use the direct URL to these add-on plans, because they are not exclusive and therefore cannot be bought by themselves. They always require an exclusive plan to also be selected (which can be any of my 3 exclusive plans).

I hope you understand what I mean...