Keep blank rows after filter

Hi everybody and apologies in advance if I'm missing something really simple. (Just haven't been able to find a solution elsewhere).

I want to filter the ateendees of a conference and then also show the activities that correspont to each ateendee, the model goes as follows.

The first filter works, i got the ateendees of the event, but as soon as i add the activities only shows the Ateendees that have activities. I would like to show all and if the attendee does not have any activities shows 0.

In this case for example, I got an event with 9 attendees:

As soon as i add the activities the result is as follows (only 7 that are the ones that has an activity):

As i mentioned i would like to show all 9 (7 with the number of activities and 2 with a 0 instead of disappear). I tried adding a measure with an IF search for ISBLANK and adding a 0 instead, but it return all the Ateendees (not only the ones in the event) with a 0.

Thanks for any help!