Documents to be submitted in order to receive a residence permit in the Republic of Latvia in connection with the family unification and you are up to the third step relative vertically or the third step relative horizontally or a brother/sister-in-law up to the third step to a citizen or a non-citizen of Latvia or to a foreigner holding a permanent residence permit: 
You shall present a valid travel document admitted in the Republic of Latvia and submit the following documents: 

Before the submission of documents of your inviter shall approve the call at the Office of Citizenship and Migration Affairs.

If you are accompanied by your minor child or a child under maintenance you shall submit all the above mentioned documents about him/her (except the marriage approving document), as well as the relationship confirming document and a permission of the other parent to reside in the Republic of Latvia notarially approved or signed in the presence of an officer of the administrative body or representation.