### Steps to reproduce

<br>

1. Set up a meeting series with e.g. 5 meetings and add _User A_ as participant

2. Begin of the insertionOpenEnd of the insertion Begin of the deletion openEnd of the deletion the first meeting

3. Navigate back to the meeting template for this meeting series

4. Add a new participant _User B_ to the series


### What is the buggy behavior?

<br>

* _User B_ will not be added as a participant to the already opened first meeting


### What is the expected behavior?

<br>

1. The participation dialog in meeting templates is extended, so that you can choose to make change to all open meetings, instead of the template

1. When selected, adding a user as a participant to the template of a meeting series also Begin of the insertionaddsEnd of the insertion Begin of the deletion addEnd of the deletion them as a participant to Begin of the insertionupcoming instantiated occurrencesEnd of the insertion Begin of the deletion already open meetingsEnd of the deletion of that Begin of the insertionseries

2. When selected, removing a participant from the template also removes them as a participant from upcoming instantiated occurrences of that series

3. Email notifications behave the same way as they do currently, with emails automatically being sent out for the series and affected occurrences

1. Closed upcoming occurrences will see updates to their participants, but no emails


End of the insertion Begin of the deletion series.


End of the deletion ### Environment information

_Please check and fill out the following details to help us identify in what versions and distributions of OpenProject the error occurs_

**OpenProject installation type**

* Hosted cloud edition


**OpenProject version**

_17.0.2_

**Browser**

* [ ] Chrome
* [ ] Firefox
* [ ] Safari
* [ ] Mobile Safari
* [x] Other (Vivaldi)

**Operating System**

* [x] Windows 11 :-(
* [ ] Mac OS X
* [ ] Mobile iOS
* [ ] Mobile Android
* [ ] Linux (please specify distro)
* [ ] Chrome OS
* [ ] Other (please specify)

**Language**

_EN/DE_