Can I save posing cards directly on my Sony A7III SD card for quick reference?

Hey fellow photographers! I have a question, and I'm hoping someone here has a clever workaround.

I'm a fashion and couples photographer based in Germany, and I use a Sony a7 III as my everyday workhorse. Like many of us, I sometimes have those moments during a shoot where my brain decides to take an unscheduled coffee break.

To help with that, I keep a collection of posing cards saved as JPEGs on my phone. They're super handy when I need to quickly show a pose to a client or get some inspiration flowing again.

What I'd love to do is save those posing cards directly onto my camera's SD card, so I can simply scroll back through the playback gallery and view them on the camera itself instead of pulling out my phone every few minutes.

I tried copying the JPEGs into the DCIM folder on the SD card, but the camera doesn't seem to recognise them. Am I guessing Sony is being picky about file structure or metadata?

Has anyone managed to do this successfully? Any tricks, tips, weird hacks, or photographer wizardry would be greatly appreciated!

Thanks in advance, and may your clients never say, "What should I do with my hands?" for the 47th time in one shoot.