The inquiry into mother and baby homes is to be picketed at 1.30pm today in Dublin by groups excluded from the investigation.
The Government has selected 14 individual institutions to be examined as part of the current inquiry.
The Coalition of Mother and Baby Home Survivors (CMABS) said this means an estimated two-thirds of victims will be potentially excluded.
"The survivor community has been sliced in two by the Terms of Reference for the Inquiry and thousands have been excluded," the group stated.
"This wanton discrimination and exclusion is insulting and deeply hurtful to our aging survivor community."
The Inquiry into Mother and Baby Homes needs to include all survivors, exclusion is damaging... https://t.co/7ikWYGI2HE— Clare Daly (@ClareDalyMEP) July 18, 2016
Theresa Tinggal was illegally adopted in Ireland over 60 years ago - hers is one of the cases which will not be examined.
"It's very, very unfair to all of us," she said.
"It's, again, another kick in the teeth, you know? What happened to us in the 50s and 60s, and actually later on, not just myself, but survivors of other institutions, was bad enough."
CMABS is also seeking a pro bono legal team "to challenge the continued exclusion and discrimination against an elderly survivor community who are dying by the hundreds and thousands every years.
"Thousands have already been denied justice and an apology in this life."