Sorry for little delay in getting back. Here I go....
To begin with, I started the conversation because the earlier expert "jgordosea" had opted out and was no longer working in this issue.
Now, coming to the point.
Yes, You are correct. Transfer pricing primarily and normally based on / concerns with transactions between companies. However, what I tried to convey is that the pattern in which you do it, I mean double invoicing your clients shows your specific intent to structure this in a manner than you evade tax. Transfer pricing transaction may involve invoicing clients from separate companies, but for the same nature of work, I am sure taxmen would not like to see it in proper spirit and you may be liable for such transfer pricing technicalities / complexities.
Because of this, I tried to focus more on "realignment" of the way you would do business. I mean, billing your customers entirely by HK company and paying the Belarus company its bills for the services taken.
This would certainly make your transactions easy and less complex to handle.
I take your point that this may spell trouble from minority shareholder of 5% stake in your Belarus company who would never earn a dividend. To counter this, I suggest to pay Belarus company for the services that it has rendered to the extent that it remains nominally in profit. You will declare dividend there if you wish as it would have a very very nominal impact as bulk of that dividend would come to you back as you are the majority share holder.
This will have double benefits. ONE - You will keep your minority stake holder away from making any noise -- TWO -- You will still keep ALL of your transactions simple, less complex all within one company and avoid any complexities arising from issues like re-invoicing and transfer pricing.
To answer your specific question -- THIS should be proposed structure and operations of your companies.
Now coming to your below point.
"............There is a really important other factor to this situation. I originally worked for my client through a IT services company in London. We then decided to open the company in Belarus as a partnership. It has so transpired that he has not taken his share of the company. So on paper its my company, but we have a verbal agreement (and documented) that he will take his share at some point........."
In this case, you still have all the more advantage to this proposed structure. He will have no point of making any accusation that you have not deliberately kept this company away from making profits. You can keep the Belarus company in minor profits to tackle with this situation. Once he takes his share on paper, you can bring this more into profit. But still I would strongly suggest to keep the structure as suggested.
Taking your question further... I was about to come to this point. I was about to suggest that if you have a very limited interest in the Belarus company and have NO strategic advantage of owning it, better relinquish it and streamline ALL your transactions dealings in your HK company. This will have operational advantage as well as add better value to it.
If you have any other questions, you may rate this positively and post another question in this thread itself if you do not want to open new thread. You will reach me directly here. For a new thread, begin your question prefixing "For Rakhivasavada...." and you will reach me.
After rating this positively, if you are done with this in particular and if you need to pay more for services, you will have option to add bonus.
Alternatively feel absolutely free to revert with more queries if you have.