Hon IME a great way to approach the constantly snotty nose that is not being seen as an 'issue' is to remind parents that when a child cannot breath fully due to congestion it reduces the OXYGEN getting to the BRAIN and therefore could affect their long term brain development if their oxygen saturation is constantly 'low' having to struggle through snot to get air into the lungs ... that usually sends most parents running for a solution to 'full oxygen access' for their child ... be it addressing the allergy through testing and finding the 'cause', going to an ENT specialist to rule out adenoids and so forth but they tend to suddenly want a 'solution'

Come at things as a sincere desire for their child's long term well being but than accept that there is only so much WE can do cause they are not our children no matter how much we grow to love and care about them..... if the parents get the answer they want from a Dr - aka their kid is normal and fine - they are going to hold onto that for dear life even in face of increasing evidence of a problem ... I have an almost 5 year old whose language development is on par with a TWO year old because he obviously has some central auditory processing issue but the parents will not 'hear it' because they took him for a hearing test at 18 months and Dr said he was 'fine' ... I am not saying he cannot HEAR I am suggesting he is not properly processing what he HEARS cause he talks like his is underwater and no one can understand him unless they KNOW him and what his 'sounds' mean! ... even his teacher has said there is an issue but even she is a ding bat cause she thinks it is a 'behaviour issue' and is 'failing' him in kindergarten rather than advocating for HELP for him