Families with a disabled child are entitled to integration assistance (https://mbjs.brandenburg.de/kinder-und-jugend/hilfen-zur-erziehung-eingliederungshilfen/eingliederungshilfen.html). The social and youth offices, health and care funds offer help.
The state of Brandenburg grants families with a low income and families, which are exposed to a special burden, e.g. as families with disabled children, a subsidy for family vacations (http://www.lasv.brandenburg.de/sixcms/detail.php/652499).
Information can also be found at: https://www.elternimnetz.de/kinder/sorgenkinder/hilfen.php