What I ended up doing is taking a small portion of ashes from each dog and mixing them together, them putting the blend of ashes into a wood casket that sits on the mantle in my living room. The rest of the ashes are buried separately in the back yard. I have a tag or something similar for each dog in the casket. I also have one for all my cats.
This isn’t for everyone, but with multiple dogs and cats, this works for me.