Sorry to hear about your pet, it must be very distressing.
Most of us who use the PDA section tend to keep one diary, and put all our news and thoughts into that one. You can change the heading to let people know that you are now writing about a different subject within your diary. If you do that it's helpful to put the page number on the new heading so that people can find where you started talking about a new subject.
If you keep to the one diary, then all your friends will be able to find you more easily, at least, that is what works for me.