Paginating Merged Element Queries I really want something like this to work but the merge function turns Elements into Arrays. I've managed to work around it other times but what's the best practice to combine two entry sets and then paginate?

{% set cat1 = craft.categories.group("catAttributes").slug('diabetic').one %}

{% set firstEntries = craft.entries.section("cats").relatedTo([cat1]) %}

{% set secondEntries = craft.entries.section("cats").showInOtherOnCatsWithNeeds('1') %}

{% set allEntries = firstEntries | merge(secondEntries) %}

{% paginate allEntries.limit(12) as pageInfo, pet %}
I think you're correct in how you currently do it. You can't merge Element Queries, you can merge IDs (or any array of anything, really). 
The only thing you should remove, is the all when settings posts, because paginate expects an element query, not an array of elements.