(( Ma'Haelun and Ma'Maln could be used as generic terms for Grand Mother/Father, literally translating as "Very Mother or "Very Father." The apostrophe may not be needed, I'm not certain, but it could be argued that the 'Grand' of grandparent is comparable to an honorific.
Then use phrases such as "Kae'leh maln'leh maln" and "Kae'leh haelun'leh haelun," to indicate a maternal or paternal grandparent.
Using this, you could create Aunt and Uncle from Mahaelun'onn and Mamaln'onn, or "Born of grandfather/mother." ))