Hi Rohan575,
1. If you don't already have the Systems Manager network created, you can do so by navigating to Organization > Create network from your Meraki Dashboard portal (note: you will need to be an Organization-level administrator with write permissions to perform this task) and selecting "EMM (Systems manager)" as the Network type.
Once created or if your EMM network is already created, you can then combine this Systems Manager network into an existing Combined hardware network by navigating to Organization > Overview, checking the box for both the Systems Manager network as well as the Combined hardware network in which you wish to combine with, followed clicking on the "Combine" button located towards the top of the table. You can read more about combining and/or splitting Dashboard networks at the following Meraki resource: Combining Dashboard Networks (Meraki KB).
2. It is a little unclear to me exactly what you are asking here but if you are simply looking to add a new Meraki hardware device into an existing Combined hardware Dashboard Network, the easiest way to do this would be to navigate to the Inventory page (Organization > Inventory), Claiming the new Meraki hardware device into your Inventory using the "Claim" button if it is not already present within your Meraki Inventory, and lastly, checking the box for the new Meraki hardware device, followed by clicking on the "Add to..." located towards the top of the table where you will then be presented with a drop-down menu where you can select the Dashboard Network that you'd like to add the new Meraki hardware device to.
If instead you are interested in how to add devices to a Systems Manager network, my recommendation would be to start with the following Meraki resource: Systems Manager Quick-Start.
3. For your question around the Meraki Dashboard API offerings, I would recommend taking a look at the Meraki Dashboard API documentation located on Cisco's Developer Hub as there you can find all of the specifics around the exact syntax required, including the available parameters for each API endpoint, examples when used with various programming languages/protocols, etc.
For example, if you'd like to query a specific Dashboard Network in order to see specific clients that are active on that network, the following "Get Network Clients" API endpoint would probably be most appropriate here.
If instead, you are curious about a device that is enrolled/managed within your Systems Manager network, the "Get Network SM Devices" API endpoint would make more sense.
I hope that information helps a bit. Be sure to let us know if I misinterpreted any of your questions. Additionally, we do have an API-specific group here on the Meraki Community which might be able to assist with more technical API inquires.
If you found this post helpful, please give it kudos. If my answer solved your problem, click "accept as solution" so that others can benefit from it.
