I recently ran into a requirement to do a PoC on a PowerApps to be able to add and update records in a single screen in PowerApps. In order to implement the PoC I decided to test this out on the Contact Entity in a Dynamics 365 environment. I did not make any changes to the Contact Entity, but just used some of the Out of the Box fields. In order to implement this, I wanted to get a look and feel of a form that would look the same whether entering new information or editing existing information.
We start by creating a blank Canvas up using the Tablet layout. This will open a blank screen. On the screen we see the message Add an item from the Insert tab or connect to data. We click on connect to data, and select either new connection if you don’t see your dynamics 365 connection from there, or if it is displayed click on the connection. Select the connection (and authenticate if required), select the dataset (instance) and then in the Choose a table, select the Contacts entity. Click on Connect. The image below shows you the Data sources window after you connected to the environment.