SIMIT CTE - Consultancy with SIMIT CTE

We would like to develope some chemical systems for our digital twin based on the SW SIMIT (Siemens).
SIMIT allows to import an FMU developed with other SW, as Modellica, but we are experiencing some troubles when importing the models.
We are facing some issues when developing our own blocks and we request some help.
We are looking for support and consultancy in how do we need to proceed and best practices.