customization in customer master & material master

Dear champs,

I have created 2 company codes under a company. Each company code is having 2 plants, 2 sales org, 2 dist channel, 4 div. I'm having customer in every sales area & material in every plant. Now i need to do any of the customer can purchase any material irespective of company code, sales area & plant.

Please give me an answar in details.

Regards