my sister and her husband wants to visit me

greetings, I am currently living in China for about 2 years with my Chinese wife (Q1 type and resident permit), we recently gave a birth to our baby boy, now my sister wants to visit us and help us take care of our baby in home for around a year or so, i have the below questions:
1.Can my sister's husband also accompany my sister to come to China with S1 type?
2.what will be the type for both of them? and do they have to apply one application form (indicating that her husband accompany her) or they need to apply seperately?
3.can both of them get the S1 visa for the 1 year stay?

*** I would like to thank this beatiful and useful website, you guys are like a guiding angel, you have beeing helped me alot through many obstacles when I got questions about marriage and stuffs previously, thanks and may God bless you all