It is not possible to extend the passes.

https://www.interrail.eu/en/interrail-passes/interrail-mobile-pass/mobile-pass-faq

Thank you AnnaB.

Can I ask if there is a limit period after the pass activation to actually use the pass?

Let’s say if I activated the pass on 1 August (latest limit for activation), what is the limit date to travel?

Many thanks

Isabelle

@Isabelle De Smedt 

What type of passes do you have?

I have the Interrail Global Pass, 7 days within 1 month

If you active the pass on the 1st of August, then you can travel until the 31st of August. If you activate the pass on the 5th of September it is valid until the 4th of October.

If you have a refundable/exchangable pass you can ask for an exchange for a pass that suites your needs better. Here's the info on refunds and exchanges:

https://www.interrail.eu/en/interrail-passes/ordering-info/refund-exchange-policy

There is a thing with the mobile pass that automatically makes the first day of validity a travel day. This might be a problem for you if you need your 7 travel days later in the validity. 

If you travel lies a bit in the future you could ask Customer Support about this problem. In that case use this form to contact Customer Support.

Hello

I still have a question.

Can I make train reservation before the activation of my pass?

Let’s say I want to take the train from Brussels to London on 01 August.

Can I already make the seat reservation?

Thanks for your help

Isabelle

Yes, you can make the resevation now. 

In Belgium, you can also just go to an international ticket office for this reservation. No booking fees there.