Houston - Relatives or nanny/au pair visa paperwork

Au Pairs
Au pairs are much easier to arrange employment for and many countries have no problem with internationals being employed under USA agreements.
Au pairs are generally unqualified and untrained. The nature of the employment is to provide overseas experience for girls or boys, so au pairs often have little childcare experience. They are therefore more suited to school age children and should not be used as an alternative to household staff or trained child care providers or nannies.

Nannies
Bringing nannies to the USA is a minefield, because many countries do not have an agreement or reciprocal employment treaty with the USA.
English nannies for example are not permitted to work legally in America at present, so check with the authorities or an agency, prior to making arrangements.
"Nanny" refers to qualified individuals holding an association recognized certificate. If you wish to employ a nanny from a foreign country, it is better to contact the social security office prior to contacting an agency, to ensure that - under the agreement of your visa - you may employ a nanny from a foreign country. The easier option is to contact an agency in Houston and employ a local nanny.

Information from an expat:
For us, the place of departure was Dubai, where we just had to pay the AUI - an annual Visa fee. It is easy and allowed to any UAE resident. As for the USA experience, the departure point was to prove that the person was working with you for at least one year - which was the case for us. Once in the US, we proceeded through a lawyer, who filed the paperwork to apply for a work permit. The work permit had to be reissued every year. It was costly, but safe and legal.