I found a workaround, not sure this is the better way but it works.
I start from the following layout :
My networks are of Wireless type. ![network1.png network1.png](https://community.meraki.com/t5/image/serverpage/image-id/2075iD5B125DD3F53FC05/image-size/large?v=v2&px=999)
First I create a new network dedicated for switches. Add devices in it and configure it.
Then, I create the switch template in addition to the Wireless template.
I combine the templates to create a unique combined template.
Now I can combine the wireless & switch networks between them
![network2.png network2.png](https://community.meraki.com/t5/image/serverpage/image-id/2077i12D6E6BADEF6A234/image-size/large?v=v2&px=999)
Done !
Maybe there is another way to save time 😉
Many thanks to all