RISE: A staff member is employed part time at the sending institution and the duration of his employment is enough to meet the 6-months criterion. While on secondment, (s)he needs to work full time for the project. Does this mean, the sending institution needs to change her/his employment agreement accordingly and employ her/him full time for the duration of the secondment?

It depends, it is certain that they need to find the necessary internal arrangements allowing the staff member to work full-time during the secondment. These arrangements can be of whatever nature provided they can finally demonstrate full-time work.