Of course you want all of your games to be represented in Steam Data Suite. If this is not the case you are welcome to add the missing items in the Games management screen. Open the settings page by clicking on the cog icon on the bottom of the menu sidebar. Then select Games at the top.
Steam Data Suite tries to help you connect all your games based on how your company is represented within Steam itself. To this end the first page of the Game management screen shows you the Steam listed companies associated with your account. Game management happens per company, so to proceed click on the company you would like to manage.
After clicking on a company, you will be shown a list of all the games known to us that are connected to that company. In this overview all the games for the company will be set active by default. If you want specific games to be excluded from SDS you can click the power button on the far right of the row corresponding with the item you want to disable. A disabled item will no longer show up in your dashboards, and will be excluded from dashboard totals. We also seize collecting data for that item.
With our Company > Game structure you will not add a single game manually, instead connect a Company. After that you are able to select what games you do or do not want to track.
Adding a company adds all games of a 'company' as it is listed on Steam, based on the name. It's only possible to add companies for which you have Steamwork access.