Need help with datamodel

Velafyko , You need have following fact

1 - Order Header (Optional)

2 -Order Details - (Order Header + Order Line)  // This will  not join with order header

3. Invoice

4. Invoice Details (Invoice + invoice Place line _ invoice Line). This will with Invoice

These facts will not join with each other 

Create common dimension like

1. Date

2. Part /material

3. Order Number , or you can use one more copy of order header as dimesion

Join dimensions with fact 1-M

refer: https://www.sqlbi.com/articles/the-importance-of-star-schemas-in-power-bi/

To get the best of the time intelligence function. Make sure you have a date calendar and it has been marked as the date in model view. Also, join it with the date column of your fact/s. Refer :radacad sqlbi My Video Series Appreciate your Kudos.