I think you are talking at cross purposes. Robert, Evie's adult Australian son who is here on a spousal visa it seems, cannot get a Thai passport just because he is married to a Thai woman and has a Thai driver's licence. Her grand daughter on the other hand may be able to travel in the way you described when she is older
I'm not sure from your post whether you are extending each of your 30 day entries by another 30 days at immigration. Giving you 60 days stay on each occasion. If not you can extend that 30 day visa exempt entry at immigration for 1900baht. You can also extend that a further week for another 1900 baht which isn't really an extension but an order to leave in 7 days. Might be useful to match up with flights on occasion. This is not as economicacal as applying for a single entry tourist visa before you leave Australia, and extending that, more for if you're already in the country and want to stay
I did the same, but found it a bit pushed time wise. You can encounter road works and numerous police stops on the way up and coming back into Mae Sai from Tacheleik there was a bit of a wait in a queue. We made it back to the Mae Sai bus station with 5 mins to spare. It was stressful doing it in this time frame and a quickly gobbled meal was hardly enjoyable but otherwise we would have been ravenous during such a long day. If I did it again, I would go earlier and allow myself more time over in Tacheleik
If you only require a short time definitely do the Mae Sai border run, it costs much less than an extension at immigration, it can be done in a day and will give you the additional 30 days as others have mentioned and can be extended for an another 30 days at immigration thus potentially giving you an extra 60 days in Thailand
The immigration office in Chiang Mai break for lunch, so either go when they open in the morning or be queuing up 15 mins or so before they return at 1.00pm. Count on being there at least a couple of hours
Patricia Wohlwend the advantage of applying for a multi entry non immigrant OA in your own country before you come to Thailand is that you get two years out of that visa by exiting and re-entering Thailand just before your first year is up. As opposed to applying for a non immigrant O within Thailand and extending this for 12 months on the basis of being aged over 50 ie applying within Thailand will only give you 12 months only
You need a photocopy of your passport ID page and a photocopy of your entry stamp into Laos, as well as your passport photos. You can do these at the Thai consulate in Vientiane cheaply 5 baht each from memory. But if you're wanting to get a low number in the queue to give you an early pick up time the following day (important if you have a plane or a bus to catch back the same day as you collect your passport with your new visa in it) then if possible try to have all your photocopies done before you get to the consulate ie ask at your guesthouse or go to an internet cafe