Prince Harry and Meghan Markle have been urged to be wary of being used to push someone else’s agenda during their upcoming international engagements. The Duke and Duchess of Sussex are set to undertake a four-day tour of Colombia this month after accepting an invitation from the nation’s vice president. The visit will not be considered a royal tour, as the Sussexes stepped back from their roles within the monarchy in 2020. The Foreign Office feels that Harry and Meghan’s visit will be “utterly irrelevant” to Britain’s interests abroad, according to a source. Another source warned that the cou…