Is it possible to achieve? I want this character to have 3 kids with her and then maybe hand her to the master for health screening and mutant implant technology.

"How does player character rub rug of Tandi?"

What the hell does that mean? What is rub rug of... ?

Well the term is a strange way of saying- How does one shag Tandi? I know it lacks the regularity of how does one fuck someone but it has to do, haha

O... k... ! Well, in that case I can only assume that your question was rhetorical, or at most not serious, since you cannot romance Tandi in any way, let alone sleep with her (she's only 16 when you first meet her, by the way). She is only a temporary companion if you rescue her from the Khans, and only until you return her to Shady Sands. So, whatever your reasoning, the answer is no, it's not possible to achieve.

Oh well Im only 17 so I guess we are a year apart, haha.

Thanks for that tip, I feel like I got to understand you better,hah. I need to go find some more ever clear.

Thats completely wrong. Actually you can, need some cha/speech check

You necro'd a three year old thread to make a fool of yourself? No, you cannot "shag" Tandi. Even with high speech check, and a suggestive option, all you can get from her is: "I'm not that kind of girl, mister! Go find a Brahmin or something." If you think otherwise, you must be using a mod.

Oh sure it is completely possible, just like how it is possible to save Aeris in Final Fantasy 7. You just need to really try hard and talk to her on uneven days except if the uneven date falls on a thursday. Do this ten times and new dialogue options appear that pertains to marriage and "having some fun".