Hello @KatSHF thanks for your post. You should be able to add the additional logos as an "image". When you edit your webpage, you'll add an image box near the bottom (or wherever you want the logo to appear). You may need to use an image editing program like Photoshop, or social media image creator like Canva, to create just one image that shows both of your other logos together.
You could also do this same image editing trick (by combining all of your logos within one image), and then using that image when uploading your official "logo". I hope this helps to answer your question.
