Importing AVCHD files

I have 2 cameeras. 1 saves in AVCHD format. The other saves in MP4. I can import the MP4 into the timeline but not the AVCHD files. Adobe is no help at all with AVCHD files but I finally found a guy on Youtube who told me how to open them and import the MTS files within the AVCHD files. So I was able to import the MTS files as if they were MP4 files. But I can't put them on the same timeline.

Any help with what should be an absurdly simple procedure much appreciated.