O Duolingo:

•  y ngŵr, y ngŵr i – my husband
• dy chwaer, dy chwaer i – your sister
• dy frawd, dy frawd di – your brother
• ei fodryb, ei fodryb e, ei fodryb o – his aunt
• ei modryb, ei modryb hi – her aunt
• ei hanti, ei hanti hi – her aunt
• eu brawd, eu brawd nhw – their brother
• eich gwraig, eich gwraig chi – your wife
• eich gŵr, eich gŵr chi – your husband
• eich chwaer, eich chwaer chi – your sister
• eich brawd, eich brawd chi – your brother
• eu hewythr, eu hewythr nhw, eu hwncl, eu hwncl nhw – their uncle

From Duolingo:

Negatives – You don’t have

• Does dim car gydag Owen. – Owen has no car; Owen doesn’t own a car.
  • Does gan Owen ddim car.
• Does ganddo fe ddim car. – He doesn’t have a car.
  • Does dim car gyda fe.
• Does gynnoch chi ddim cath.  – You don’t have a cat.
• Does dim cath gydag Olwen. – Olwen doesn’t have a cat.

From Duolingo:
Questions – Do you have, Do you own?

• Oes car gyda chi? – Do you have a car?
• Oes car gynnoch chi?
• Oes gynnoch chi gar?
• Oes gen ti gath? – Do you have a cat?
• Oes cath gydag Owen? – Does Owen have a cat?
• Oes ganddyn nhw gath? – Do they have a cat?
  
• Oes – yes
• Nac oes – no
• Oes gan Olwen gath? – Does Olwen have a cat?
• Nac oes, mae gynni hi ddau gi. – No, she has two dogs

From Duolingo:

To have, to own

• Mae car gyda fi. – I have/own a car (lit. “There is a car with me.”)
• Mae cath gyda Sioned. – Sioned has a cat.
• Mae pannas gydag Owen. – Owen has some parsnips.
• Mae cath gan Sioned. – Sioned has a cat.
• Mae gen i gar. – I own a car.
• Mae gan Sioned gath. – Sioned has a cat.
• Mae gynno fo bannas. – He has some parsnips.
• Mae gynno fo gar. / Mae car gyda fe. – He has a car.
• gen i – with me
• gen ti – with you
• ganddo/gynno fe/fo – with him
• ganddi/gynni hi – with her
• gynnon ni – with us
• gynnoch chi – with you
• gynnon nhw – with them

From Duolingo:

Possessive (“Genitive case”):

• [het] [Owen] – [hat] of [Owen]; Owen’s Hat
• [pannas] [Owen] – [parsnips] of [Owen]; Owen’s parsnips
• [cath] [Olwen] – [cat] of [Owen]; Olwen’s cat
• [tŷ mawr] [Siôn a Sioned] – [Siôn and Sioned]’s [large house]
• [siop fach] [Gruff] – [Gruff]’s [little shop]