[Grammar] Diagramming

Could you diagram this sentence for me? I've tried to diagram it but i still have some problems.

"Criminals staked out a business, sometimes calling to ask for closing times, then trailed the owners home."

[Soup]

Hi Andy

Look for what is not there:

Criminals staked out a business, [and they] sometimes call(ing) to ask for closing times, then [they] trailed the owners home.

The following phrases are reduced clauses:

• sometimes calling = sometimes they call
• then trailed = then they trailed