The 72-year-old from Glasgow, who has looked after her granddaughter for 16 years, said: "If I hadn't stepped in she would have gone into the system and been pushed from pillar to post."
She said she believes the work of kinship carers across the country is undervalued and not recognised by the authorities, who would otherwise have to pick up the bill for looking after vulnerable children.
By taking in relatives, she said, families are saving the government money in care and fostering costs.
However, unlike foster carers, not all kinship carers receive allowances to fund the care of the children.
She said: "I want the Scottish Government to stop discriminating against kinship carers.
"People are angry. Foster carers are getting money for buying clothes for the children they look after.
"There are a lot of kinship carers looking after family who are finding it hard to pay bills or their mortgage.
"I'm looking for the government to put some money into the kinship care system. We are not supported in caring for children.
"It's not a question of whether we have a choice.
"I had my man when I took on my granddaughter but he died seven years ago. Things are difficult."
Mrs Brownlie is to join the protesters in the day of action at Holyrood.
She said: "We have to have our voice heard."