You should be made aware that if you are applying for an Australian settlement or fiancee visa for your Thai partner to live in Australia your Thai partner as part of the application after you have submitted the application to the Australian VFS in Bangkok your Thai partner will be asked to attend a designated hospital for a full body medical.
As part of this process if your Thai partner has children from a previous relationship and not traveling to Australia they will still have to have a body medical with their mother and this is in case of any future visa applications for the children the Australia Immigration and Migration rules states that all children should be medically checked with the applicant.
So in preparation of this make sure you have access to the Thai children to take them for a medical and also that the Thai children have Thai passports or Thai Identification cards before the application is presented because no access to the children then no visa for your Thai partner/ Thai wife. It is important that you are made aware of this as nobody likes surprises.