Module to make one attribute depend on the other

[30knees]

See this post for an explanation and the history behind the idea: https://forum.thirtybees.com/topic/806/using-packs-and-combinations-a-possibility-or-is-there-another-solution/7

Basically, I'd like to be able to sell

Product: Widget Combination A: 1 Widget Combination B: 1 Widget Family Pack (10 x Widgets)

And I'd like to manage by stock only via Combination A.

That means that if I enter

Quantities Combination A: 100 Widgets

and I can specify somewhere that

Combination B is dependent on Combination A and that 1 x Combination B = 10 x Combination A,

the system will be able to calculate that

the stock should be as follows:

100 x Combination A 10 x Combination B

but

99 x Combination A 9 x Combination B

Hope this was clear :-)