Always include default stores in result list

Hello!

Is it possible to set a number of default stores that are always included in the result list?

I have tried doing this by sql, and got as far as the query below, but it simply returns zero results. (As a curiosa, the query works perfectly when run with sample lat-lng values in phpmyadmin, just not in the plugin)

SELECT lat, lng, ID, distance FROM (
SELECT post_lat.meta_value AS lat, post_lng.meta_value AS lng, posts.ID, 
( %d * acos( cos( radians( %s ) ) * cos( radians( post_lat.meta_value ) ) * cos( radians( post_lng.meta_value ) - radians( %s ) ) + sin( radians( %s ) ) * sin( radians( post_lat.meta_value ) ) ) ) AS distance
FROM $wpdb->posts AS posts
INNER JOIN $wpdb->postmeta AS post_lat ON post_lat.post_id = posts.ID AND post_lat.meta_key = 'wpsl_lat'
INNER JOIN $wpdb->postmeta AS post_lng ON post_lng.post_id = posts.ID AND post_lng.meta_key = 'wpsl_lng'
WHERE posts.post_type = 'wpsl_stores' AND posts.post_status = 'publish'
GROUP BY posts.ID, post_lat.meta_value, post_lng.meta_value $sql_sort)
UNION  
SELECT lat, lng, ID, distance FROM (
SELECT post_lat.meta_value AS lat, post_lng.meta_value AS lng, posts.ID, 
( %d * acos( cos( radians( %s ) ) * cos( radians( post_lat.meta_value ) ) * cos( radians( post_lng.meta_value ) - radians( %s ) ) + sin( radians( %s ) ) * sin( radians( post_lat.meta_value ) ) ) ) AS distance
FROM $wpdb->posts AS posts
INNER JOIN $wpdb->postmeta AS post_lat ON post_lat.post_id = posts.ID AND post_lat.meta_key = 'wpsl_lat'
INNER JOIN $wpdb->postmeta AS post_lng ON post_lng.post_id = posts.ID AND post_lng.meta_key = 'wpsl_lng'
WHERE posts.post_type = 'wpsl_stores' AND posts.post_status = 'publish' 
AND (posts.ID = '1706' OR posts.ID = '2835')
GROUP BY posts.ID, post_lat.meta_value, post_lng.meta_value)

Regards,
Susanna