Up to you really - I'd just let them grow as they are for a while, and I'd also be inclined to chop down the original, if its looking unattractive and unwell, and let the new growth take over. If they grow on some more, it might be possible next year to take a sharp knife and separate out individual plantlets, but you need to get some root section with each one, or they'll just die.

the other option is just leave them as they will be ok. they wont hurt each other as they are geneticly the same plant but as bamboo sais id cut the parent plant down .

Thanks , going to let them grow , hopefully get couple new trees, the main plant still looks tatty , but there is slow groth from the top , and i realy dont want to cut it down , was the fist plant i planted in garden and sort of sentimental..will give it few more months if the groth dont increase i will cut it down...fingers crossed for some sunny days and lots of rain.

if its growing its ok just wrap them all up winter and cut the dead leaves off.

Omg i seem to have another 4 plants growing at the base....the main trunk slill looks a sorry state.

just be patiant it will look amazing