I know one year I included Annabelle and put brackets around her name
eg Greg, Tash, Nic, (Annabelle) and Samuel.
I got a good response from some dear friends who included her the same in their cards back to us. Some of Roberts family were aghast and thought it very wrong to put her name in and were very upset and complained to MIL about us. (gee get a life will ya) and otehrs had absolutely no idea at all...
In the end it is whatever feels right for you.
We started off too the first few years we would buy a gift and put it under the Giving Tree at K Mart or Target and we bought a gift that we would have bought for Annabelle that year/age if she had lived.
hugs
Jude