From the experience of a colleague

When my colleague had to undergo a surgery and then was unable to work for 2 months. The situation was communicated to the project manager with in the consortium (ITN), the host institute in Germany gave him a new contract for the extended period. However, there was no mention of such possibility for extension in the initial contract he received from LMU. The calculation of alloted project funds are made for person months and when it is not consumed, they remain and can be consumed if it is well with in the project time frame. There might be some ammendment that need to be filed and approved in these situations.

Usually, the EU stipulations will be followed by the University and the contracts do not necessarily cover all aspects of such stipulations. It is not surprising that this is not included, however you can ask for clarifications.