How can I connect my online ordering platforms and delivery services directly to my point-of-sale system?

We ask the same underlying question in different ways.

• How can I connect my online ordering platforms and delivery services directly to my point-of-sale system?
• How do I integrate third-party delivery services and online ordering platforms directly into my point-of-sale software?
• My restaurant uses multiple online ordering and delivery services. How can I integrate them all into my POS?