You should check out this guide:
https://wiki.mikrotik.com/wiki/Manual:L ... less_links
Also read a note about LACP and why it is not the best choice in this type of setup.
If you are not able to add a logical interface into a bond on your Cisco, then there will be no other way to make this work without adding extra hardware. You could try to find a MAC address and an IP address that would generate a different hash for each device, but this is still unreliable.