Keep an eye on development. My guess is the doctors may not really give it a label until the 18 month mark. They're usually looking for non-walkers at that point( if the child hasn't caught up by then) All you can do is put trust in the parents. I've had a child at 15 months still barely able to self-feed/not walking/barely putting weight on legs/not able to hold own sippy cup etc. and then found out from the parents through a conversation 3 months later that they were an attachment parenting family. I had no idea! Child was carried in a sling/spoon fed puree/bottle was held for child etc. That was my AHA moment! You never know what the true cause is. The 15 month and 18 month checkups with the family doc will highlight delays if they still exist at that point. Support the child the best you can. If the family is going to PT/OT, ask for suggestions of what you could replicate at daycare to help.