Pre-Filter Page from Dynamics

Hello everyone!

I need to bring in Power BI customer dimension from Dynamics Business Central: each customer has a region as its dimension (Table 18 of Dynamics). However, using Dynamics functionality (i.e. Web Services) I'm not able to connect to the table itself, I have to use Pages or Queries. I found 2 pages that should contain the information I need (DimensionValues and DimensionLines). I can easily bring DimensionValues in Power BI, but when it comes to DimensionLines, I got the following error message:

"DataSource.Error: Dynamics365BusinessCentral: Request failed: The remote server returned an error: (400) Bad Request. (You must specify a parent id to get the lines. CorrelationId: SomeValue.)"

It seems I need to "pre-filter" Navigation step in some way but I have no idea how to correctly replace [Data] with [Data With Filter]. In addition, because of this error I can't even see a page structure so I don't know what columns are present there and how they are called. I wish I could load only first row, understand DimensionLines page structure and then filter the correct column with a value from DimensionValues table.

Thank you!