Morning Ted and your cute cat, or Cute cat and Slave,
I’m sure you’ve tried everything but here’s a few things I noticed when looking at the docs I found.
1. The spelling was mainly phonetic i.e. Salomon for Sullivan, Flewri for Florrie, etc.,
2. Within the docs, which make up the file, on some my Grandmother is called Florrie, or Flewri or Florence Elizabeth Lucia! And the index made it look like there were several of her.
3. My twins were born 1891 but their births were not registered until 1892 when I believe they needed to complete immigration records. Infact, the twins were born in the March of 1891 but in the immigration records written September 1892 it is claimed they had only been in Antwerp for 2 months. Another sibling was registered at the same time as the twins and a scribbled note mentions another sib born in 1894.
I also wondered whether you had tried looking for them under the mothers maiden name? Or perhaps they went with cousins or the parents siblings? There may be a good reason for the leaving the UK and perhaps not wanting to be found?
You could always try searching the Belgium records...... but it might be that Belgium is a blind as continental Europe tends to bleed from one country to another quite easily.
Whichever way, good luck with your search and if you find out why they went to Belgium I would be very interested, as my family appear to have gone there in 1891 but were back in the UK by 1900 which is about the same time as yours.