Buying out joint beneficiary when they live abroad

My mother has passed and her estate mainly comprises of her bungalow. Other than a couple of gifts it is to be divided three ways - between my sister and myself and her grandson. I wish to buy the other two out and a price has been agreed and probate granted. My sister and myself are the executers. My problem is that her grandson lives in Canada. Can transfer still be done and if so what is needed in these circumstances to transfer the title to me? 

Susan - I am sorry to read of your loss. If I have understood correctly your late Mother was the sole owner of the registered property. If so then the property can be transferred by the executors - see our online assisted guidance for the forms and more you will need
If her grandson is a beneficiary only then he need not be involved in the transfer of the legal ownership itself

Thank you very much I was led to understand from the Probate solicitor that her grandson needed to be involved and was going to go through the process of an actual sale of the property by  the executors and purchase by me. Funds to enable me to pay the 2/3rds of the Probate valuation would need to be obtained from the sale of my present property. How long would the transfer of legal ownership take with you to enable me to move in? 

Susan - you should always follow your legal advice although worth confirming what needs to be done with a conveyancing solicitor as well.
I don't quite follow what it is you are now asking although it reads like you want to sell your own property before you then deal with the deceased's property and move in there.
If you are applying to HMLR for the register to be updated in anyway and there is then an urgency involved you can submit the application first and then request expedition 
Expedition can reduce the wait time from a few months to a couple of weeks but everything then needs to be in order of course to enable the register to be updated as applied for.
You don;t have to wait for a purchase to be registered before 'moving in'. Many purchasers complete and move in. The register update then happens later