First of all, a debt management plan should not be contractually binding, so while you may have agreed to certain terms or conditions of business, you should not be tied to the agreement. Only the likes of an IVA would be legally binding, and could not be passed outside the UK. If you resided outside the UK you couldn't even enter into this type of agreement.
We have just started dealing with a UK company this week, who are withdrawing for similar reasons, ie the enforcement of Central Bank regulations, but in order for us to get hold of the new customer's file, we have to contact each customer, explain the position, and give the customer the option of moving to our service.
In our case, we cannot access anyone's personal data without the consent of the individual, so we require them to sign a new Letter of Authority to Act. Once this has been obtained, we can then request the client's file be sent over. If the customer does not want to move, they cannot be forced to move to any company, or can set up a new agreement elsewhere.
Before any of this has happened, the UK company has also had to contact each individual customer to explain the situation to their own customers, and get their consent to pass the customer's contact information on to us, in order that we can then contact the customer.
This is the arrangement we have, but I cannot comment for certain on other companies' arrangements. As the original agreement you may have had was with a UK company, it is likely that the agreement would fall under UK data protection laws, and under these laws, a data protection agreement may have been set up between the two companies allowing them to exchange the relevant information.
Hopefully this may put your mind at rest. Have a look at your terms and conditions if you still have them, and you should see that you are not tied contractually to this company, nor are you obliged to move where they tell you to. However, it's actually good practice to have a back-up for their client's in this eventuality, rather than leaving people at the mercy of their creditors. It could have been far worse if they simply turned their back on their Irish customers.
PS The regulations should also be welcomed, as they are designed to protect consumers, and by engaging with an Irish company, there is a safety net. The Central Bank have been going through every Irish company with a fine tooth comb over the last three months, and those who have had issues regarding client funds have been closed down by the Central Bank.