Are conditional products possible ?

I would like to define product A
and also products A1 A2 A3

But products A1 A2 A3 should only be available for purchase on condition that the user/client has already purchased product A.
Product A will likely have been purchased some time in the past.
If not yet purchased then A1 A2 A3 can only be purchased together with A.
( having to buy A first and later A1 A2 A3 so in 2 steps would also be acceptable )

Is this possible with the standard version(s) ?
If not how difficult would it be to accomplish this with custom programming ?

Thanks.

I've tried it on the demo site but doesn't quite work.

If you purchase product A you become a member of GroupA.
Products A1 A2 A3 depend on membership of GroupA

If A1 A2 A3 are options to A then they do not show as options,
since A has not yet been purchased this makes sense as you are not yet a member of the GroupA.
To get the options A1 A2 A3 you would have to buy A and then re-buy A with options.

Without the options, A1 A2 A3 as seperate products you get a 2 stage process,
first buy A and then you can buy A1 A2 A3 in a second purchase, acceptable for me.

Problem is i want people to see A1 A2 A3 right from the start, so they know those products exist, what the specifications are, what the price is and so on, just not be able to buy them. ( it would be pointless to buy A1 without having A as A1 is completely useless without A )

So i tried this:
Define products A A1 A2 A3 as available to all and A1 A2 A3 options of A.
Then i put A in category A and made the category available to all.
Then i put A1 A2 A3 in a sub-category and made that category dependend on membership of GroupA
Now i only get to see A with 3 options, so there i can do a group sale.
Once purchased i then get to see the sub-category with A1 A2 A3 and i can add a product without having to re-buy A.
Still not quite what i want but close.


Question:
How difficult would it be to add a condition to a sale ?
So define A A1 A2 A3 as products visible to all, allowing A1 A2 A3 to be options to A so a group sale is possible.
But generate a warning and refuse a sale for A1 A2 A3
unless the client already purchased A OR is purchasing A at the same time.

It would be great when a user is viewing A2 for example that the 'Add to cart' is not present with a message 'This product can only be purchsed .after product A has been purchased. (or together with product A)'
The same message would need to appear for users not yet logged in.

Thanks,
i'll look into the second option,
makes more sense and seems more robust to me.