Hi. I have an MPhil degree (2015). I would have upgraded to the PhD but to put it nicely, the 'university supervisory system was broken' and I got short-changed. So I decided to cut my losses and run! But I decided to get something tangible for all the that hard work and research, namely, the MPhil. As the proverbial saying goes, a bird in the hand is worth two in the bush.
To get some intrinsic satisfaction from this decision, I decided to convert my MPhil in a book trilogy. The first book has been published and was well received and already in school libraries. The others are due this year (2018) and early next year. Taken together, the three books would eventually cover more than 80,000 words (the length of a PhD thesis).
Now, I lecture full-time (on contract) at a university but if I am to transition to a full Lecturer, I need a PhD according to the 'system'. So now my questions. Is it possible for me to upgrade my already-received MPhil to a PhD of the same topic without having to start over with a new topic? And in a short time frame? Are there universities where I can do a PhD by Publication with just three books and a couple articles? Is there an online route to such PhDs? Please note that cost is a factor here given the cost of having had to educate my children at university (including medical school). So I am not getting any younger and the bureaucratic door of the university system is fast closing on those without a PhD.

Normally you can't use publications from a previous degree eg master to automatically qualify for a higher degree eg PhD. Usually you will also have to work on a new project although the project can be an extension of your previous work. It will have to be a body of work that will demonstrate min 3 years of research.

I looked into doing a PhD by publication a few years ago and to the honest the requirements seemed to vary. Some universities will only do them for previous students. I remember one I looked at wanted you to produce 6 papers within two years of starting your PhD and I think you had to be first author on 5 of them, whereas my old uni had no time limit, you could use past papers and didn't have to be first authors on them (although you need to be pretty well involved to talk about them in the detail needed for a viva).

I think the best thing you can do is find universities that do it (I'd start with the ones you went to) and ask them.