I could. We don't really use it that way often since it can be a risk.

[ Marco decides not to explain the moral reason why the Animorphs don't morph sentient beings. Maybe later, if Marco feels comfortable about talking the technicalities. ]

Not to mention morphing people here is a little useless - the wings they sewed on their back don't change at all. If I morph you right now, it won't take long for people to know you well can notice the wings are different.