[Storyteller.]

Oh my goodness, I am so sorry! I thought I'd replied to this already.

First of all, I'm so sorry for your loss. Even when a pet passes away naturally of old age, it's difficult - especially if they leave family behind. In terms of keeping your remaining rats occupied, I think the best thing is to give them as much enrichment as you can, and to change it up often. Change the layout of their cage, the toys and treats they have, everything that could make it more exciting for them. Ideally you should probably do it before you go to work or whenever you're going to be away for a long time so that it gives your rats something to do while they're alone. You could even ask your parents to pitch in if they're comfortable with it; if they're home while you're not you could ask them to add in some enrichment during the day to keep things fresh.

Sorry again that this is such a late reply. I'm still on leave and slowly working up to being active again, and as you can see I'm not exactly on top of everything yet. Hopefully this still helped though.