Hi Elias 

Thanks for posting in the Lucidchart Community! Just to make sure I understand the issue you are experiencing correctly you have created custom shapes using existing objects from our native shape libraries but when dragging those custom shapes from the custom shape library onto the canvas they misshape? If that's the case I believe the issue you are seeing is caused by Line Connections being enabled on your document. When this feature is turned on lines automatically adjust connection points to form the most efficient path between the two objects on the canvas. You can disable Line Connections in your Page Settings by navigating to File > Page Settings > Lines. For more information about this please review our Work with Lines article. 

While it is currently not possible to create an "unchangeable" custom shape out of the existing elements you are using that would allow you to choose the points to connect turning off Line Connections will give you more autonomy to connect your custom shape to other elements on your canvas without altering its format.  

Please note that turning off Line Connections will prevent you from creating custom shapes with the same functionality as you would have if that feature was enabled. Because of this I would recommend disabling this only when using shapes that you have already added to your custom shape library.  

For those interested in learning more about how to create advanced custom shapes and add them to custom libraries please check out our Modify Format and Style Shapes and Shape Libraries articles from the Lucidchart Help Center. 

Hope this helps!