You can Copy files to other Moxo Conversations.
Desktop:
1. Open the conversation.
2. Hover over to the file which you wish to Copy.
3. Click on the 
three dots icon and choose Copy To...
4. Select the destination Conversation and click on Save.
Mobile:
1. Open the conversation.
2. Tap and hold on the file you’d like to Copy.
3. Tap on Copy To…
4. Select the destination conversation and tap on Copy.