Hi thank you for your question.
It is possible for them to join you in the UK provided you can statify the immigration requirements the requirements are as follows:
(f) one parent or a relative is present and settled in the United Kingdom or being admitted on the same occasion for settlement and there are serious and compelling family or other considerations which make exclusion of the child undesirable and suitable arrangements have been made for the child's care; and
(ii) is under the age of 18; and
(iii) is not leading an independent life, is unmarried and is not a civil partner, and has not formed an independent family unit; and
(iv) can, and will, be accommodated adequately by the parent, parents or relative the child is seeking to join without recourse to public funds in accommodation which the parent, parents or relative the child is seeking to join, own or occupy exclusively; and
(v) can, and will, be maintained adequately by the parent, parents, or relative the child is seeking to join, without recourse to public funds; and
(vi) holds a valid United Kingdom entry clearance for entry in this capacity; and
(vii) does not have one or more unspent convictions within the meaning of the Rehabilitation of Offenders Act 1974.
You will need to provide documentry evidence for each part of the rule for example custody documents, evidence that one of the parent had died and the other is unattainable, you will need to provide evidence that you have the required funds and accomodation for the children, also evidence of monies you may have been sending them as well as records of telephone calls emails ect which you have used to stay in contact with them.
If you can satify the UKBA that there is compassionate and compelling circumstances that the children should be in your care here in the UK then there is a chance you will be successful. I would recommend that you provide a vast amount of documentry evidence for your case.
I hope this answers the question. If so, kindly click ACCEPT.