You should only offer plain paper with no inks or dyes. However, letting them shred paper can trigger their hormones and cause a female to start laying eggs. If you have all three birds in one cage, at some point they are going to start fighting. It’s never a good idea to have an odd number of birds in the same cage. Two will end up bonding and the odd bird will get picked on and bullied, even if they are all make or all female. Lovebirds can be extremely aggressive towards each other. As for things to keep them busy, there are plenty of safe toys available for lovebirds and this would be the best thing for them.
Thank you for asking Lafeber,