Ungrandmotherly

Left without a mother in his infancy—perhaps that was what prevented him from achieving the highest fame as an author—his father placed him with a grandmother, who, in a singularly ungrandmotherly way, cheated him out of the appropriations for his education.

Source: wiktionary

Here, therefore, we have Mrs Wimbush, a comely widow, with a daughter somewhat prematurely developed, on the one hand, and with a mother persistently juvenile and evergreen, on the other: Mrs Wimbush and her daughter Carry living together in Whittington Lodge, Highgate; Mrs Marrables, the youthful and the ungrandmotherly, dwelling by herself at Taunton, and devoting her time to collecting subscriptions for different charitable objects, not forgetting her own rents.

Source: wiktionary

She stood with her back to the fireplace, looking very ungrandmotherly in her tailored slacks and silk sweater.

Source: wiktionary

She had never known her grandmother, on either side, and when she was little she was a bit resentful that Theresa was such a drastically ungrandmotherly type.

Source: wiktionary