Should I Help Parent Buy a Home?

My parents immigrated to United States from a 3rd world country nearly 30 years ago and had always dreamt of owning a home. They’ve made many financial sacrifices to raise me and my sister while my father had to build his way up to a stable career. We’ve been living in an apartment since their move to the US.

Now my parents want me to help them purchase a house in CA. I (26 yo) with annual salary of $93K will be co-signing with my father (60 yo) $130K.
My mother (67 yo) is unemployed and my sister (31 yo) will pay rent for the next year or two before moving in with her fiancé. My friend has also agreed to renting a room for years to come (work location purposes). The agreement is that I will eventually become the owner when my parents pass.

My girlfriend’s situation is much different. Her primary home in wealthy neighborhood is currently being rebuilt. Her parents also own a secondary home that is rented out to pay for bills and they live in a third home in another state. So this would not be her 1st home.

I’ve been living in an apartment with my girlfriend for about a year now and we always talk about how wonderful it would be to own a house together. I realize this is my chance to help my parents achieve their dream but I also understand this decision will make it difficult for me to purchase a home with my significant other for the foreseeable future.

Any advice would be appreciated…