A few ideas…
[name_f][/name_f]Grandta / GrandTa
[name_f][/name_f]Grandear (this is what my cousins and their aunts/dad called one of their grandparents)
[name_f][/name_f][name_f]Tati[/name_f] / Tattie
[name_f][/name_f][name_f]Tally[/name_f]
[name_f][/name_f][name_m]Tanny[/name_m]
[name_f][/name_f]Tibbs
[name_f][/name_f][name_f]Tibby[/name_f] [name_f][/name_f] / [name_f]Tabby[/name_f]
[name_f][/name_f][name_f]Nanny[/name_f]
[name_f][/name_f][name_m]Taz[/name_m] / Tazi / Tazzie
[name_f][/name_f]Tizzy
[name_f][/name_f]Fizzy
[name_f][/name_f][name_f]Goldie[/name_f]
[name_f][/name_f]I used to call my great grandad ‘Mate’ because he used to call everyone ‘mate’ so it stuck!