Bradley crates are vanilla

Edit the \oxide\data\BetterLoot\LootTables.json  with the plugin unloaded , edit , save, reload plugin.
Make sure that this setting is set to true
"assets/prefabs/npc/m2bradley/bradley_crate.prefab": {
"Enabled": true,

And add items you want in that section

Remember advise that has already been given for the same type of subject
https://umod.org/community/better-loot/36356-crate-loots-are-terrible?page=1#post-4