How to render data in different formats together? sunch as 3DGSresult with glb in nerfstudio-viser

[smart4654154]

Hello, I have added a flower in the 3DGS scene.flower is in glb format
I think the data format of 3DGS is different from that of flowers, but they were successfully rendered together.
Another example, I added an image to the 3DGS scene and successfully rendered them.

As far as I know, Viser is just a web page used to receive rendered images, and then Viser displays the results images on a web page. This may mean that the 3DGS result is rendered simultaneously with the flower, generating only one result image.
I want to know the principle, can anyone help me?
Thank you