Could ye say something like "ní sasta ar an múinteoir leis na daltaí"?
No. sásta is an adjective, not a noun. It can't be ar someone.
I was thinking something like that after alright. Thanks.
why not ndaltaí as in "Cad iad dearchtaí na ndaltaí"? Is it because it is not a phrase like "Poblacht na hÉireann"?
In dearchtaí na ndaltaí, dalta is in the tuiseal ginideach ("of the students"). In sásta leis na daltaí, dalta is in the tuiseal tabharthach. Different rules apply.
How about Mic léinn?
Should be accepted, yes.
why is lena daltai wrong?
lena daltaí means "with her students".