Well said Pipper. I live in Bulgaria and work in the property business. Sure there are some awful companies, usually the larger ones and ones that operate pushing apartments on the coast and in the ski resorts but there are some of us that pride ourselves on good service and honest advice.
To answer the original question though, I think you will need to sell to your family members, unless you can just asign your shares. You cannot simply change the names of the owners in the UK for property and cannot do the same here - you need to formally sell or assign the shares in the property. And if you are not selling to them for a huge profit (and cannot see how you could be really with market way it is along the coast) there will be no capital gain. Why not ask the lawyer you got to act on your behalf when purchasing the apartment. Should not cost much to do this.
Rachel