After years of bureaucratic uncertainty, Shaun Douglas-Galley is now legally-recognised as the father of his two adopted sons.

"It's a celebration to be had, that our families are now recognised legally and we feel more secure," he said.

Shaun and his partner Blue Douglas-Galley moved to South Australia from England in 2013 with their sons Joshe and Dylan, now aged six and three respectively.

But because same-sex adoption was illegal in the state, the couple's legal status as the boys' parents was uncertain.

The pair spearheaded a campaign to legalise adoption for same-sex couples, which led to law changes which passed Parliament late last year.

Today, they come into effect, bringing South Australia into line with all other states.

"It's well overdue, this law," Shaun Douglas-Galley said.

While Elise Duffield (right) gave birth to Tadgh, Sally Amazon (left) is now listed on his birth certificate as well. ( ABC News )

"We are exactly the same as every other family; the boys are safe, they're loved, they have very good, strong female characters in their lives and the boys are happy and that's all that matters.

"They know they are in a legal family, no different to any of their peers at school."

It was a different law change that, late last year, changed the lives of Elise Duffield and Sally Amazon, parents to two-year-old Tadgh.

While Ms Duffield gave birth to Tadgh, Ms Amazon was finally able to be listed on his birth certificate.

Ms Amazon said the adoption change was a huge step forward for other parents.

"It is great every time one of these laws catches up," she said.

"I don't think people understand the difference it makes in the lives of people in our community; the recognition it provides, the normalcy.

"For other same-sex couples it will mean everything to them, it'll mean their lives will change, and it means security for couples like Shaun and Blue."