I am trying to fill in three ‘embed’ fields when creating companies. It seems to me that additional fields should appear so that I can fill them in, but they do not appear.
Do you have a solution?
Thanks in advance 
Welcome to the Make community!
You can try using the universal (Make an API Call) module to call the endpoints that allow updating of embed fields.
See if such an endpoint exist in the Sellsy Developer API reference. If it exists, you can integrate the endpoint in Make using the app’s universal module (Make an API call) or generic HTTP “Make a request” module.
You can also suggest for custom fields to be supported, in the Idea Exchange. However, do search for a similar request (and also upvote), just in case it has already been suggested to avoid duplicates.
If you need assistance in setting up the app’s universal module, or the built-in generic HTTP modules, please provide additional information about what you have tried in relation to the external service’s Developer API Reference — how you are setting the connection up, a link to the endpoint are you trying to connect to, and what errors you are encountering.
You can also complete this brand new course/tutorial in the Make Academy on how to use external APIs — API calls with HTTP modules
- API and Endpoints
- Header and body
- Multipart/form-data
- OAuth 2.0
Hope this helps! Let me know if there are any further questions or issues.
— @samliew
P.S.: investing some effort into the tutorials in the Make Academy will save you lots of time and frustration using Make!