Settling during secondments in a new country

Hello everyone,

I would like to ask for some advice to anyone that has followed a Joint Doctorate Program or who had long term secondmens (more than 6 months) during their Doctoral project.

Normally each PhD student (non EU citizen) holds a resident permit of the country where the host institution is located; however, it seems necessary to obtain another resident permit to settle in a different EU country during the secondment. It remains unclear if I need to notify the temporary leave from my main country, if by only having an adress at the country of secondment would affect the contract with the host institution and if this would cancel my first resident permit (Blue Card). How have you handled these admnistrative aspects?

I would much appreciate if you could share any information.

Best regards,