Merge and Append solve different preparation tasks. Merge Queries matches rows using key columns and adds a nested table of matching records. Expand that table to bring the required fields into the result. Append Queries stacks compatible records from another query underneath the current ones.
Choose the join kind deliberately. A Left Outer merge retains every record from the first query, with null lookup values where no key matches. An Inner merge keeps only matching records. Duplicate keys in the lookup can create multiple output rows after expansion, so check the lookup's intended grain before trusting a total.
Text keys must match their actual values. Trim unwanted spaces before merging depot names. After expanding, keep only the lookup columns you need. For append, inspect column names and types; matching by position isn't the same as matching by column name. Finish with Close & Load.