MSPs are due to debate the Children and Young People Bill and the campaigners want an amendment backed which will protect or increase the assistance for kinship carers.
The campaigners argue the new Kinship Care orders gives less support than children currently receive if they have looked after status, while being cared for by a relative, often a grandparent.
The Kinship Care Alliance argues the new orders will reduce the number of children with looked after status which reduces financial support.
Removing looked after status in favour of a Kinship Care Order they argue will remove the priority access to psychological support many of the children require.
They also want a minimum level of financial support provided by local authorities to cover the cost of basic childcare.
Up to 1000 campaigners and supporters are expected to protest outside the Scottish Parliament next Wednesday when the Bill is to be considered by MSPs.
Anne Schwartz, chairwoman of Scottish Kinship Care Alliance, said: "It is despicable that the Scottish Government is trying to further reduce support, which is already inadequate, under this Bill.
"Children in kinship care should not suffer because their family members have taken them into their care, where they have maximum stability and love, rather than letting them go into the foster or residential care systems.
"These children have comparable needs and should have access to the same services as those in other forms of care."
Tina Hendry, a Kinship carer who is deputy chairwoman of the Alliance, said children in kinship care are experiencing a range of problems that require additional help.