Maximum duration of stay in North America on visitor visas to US and Canada

[karigerr]

My parents are planning to visit my sister in Canada for few months and then come visit me in the US. I want to know if their stay in the US is impacted by their allowed duration of entry into Canada. Extending this question even further, is it possible for them to spend more than a year in North America by traveling multiple times between Canada and the US? Another question I'm looking answer for is if they can travel from India on a one-way ticket. Thank you very much for your help!

[peace999]

Last question first; they cannot travel on a one way ticket when they have a visitor visa. The airline + Indian immigration will not let them board, and even if they did,
the US/canadian immigration will create serious problems suspecting them to be potential immigrants.

And they can spend one year in North america. 6 months in US + 6 mnths in canada but with only one entry for each country. they won't be allowed to reenter
US or canada whatever the case may be without having spent a significant period in India.

[karigerr]

Thanks a lot for the prompt reply!!

Can you also clarify this scenario: they first spend about three months in Canada, then upto six in the US, and then return to Canada for another three months in Canada before departure for India? Or is it that once they depart Canada they cannot re-enter from US if their stay in the US extends beyond six months of their arrival date in Canada?

I really appreciate your advice.