The DUP, SDLP and Alliance have jointly suggested changes to the government's Brexit legislation.
The parties want a legal guarantee that Northern Ireland businesses will have "unfettered access" to the rest of the UK, and the amendments are being backed by NI business groups.
MPs will continue debating the legislation on Tuesday.
Parliament voted overwhelmingly to back Boris Johnson's Brexit deal last month, but NI MPs voted against it.
SDLP and Alliance oppose Brexit while the DUP says the deal would undermine Northern Ireland's place in the UK.
Each of the parties has tabled a series of their own amendments as well the joint efforts.
It will be up to the House of Commons speaker to determine which amendments are selected for debate.
The speaker is likely to select those with cross-party support.
However, even if selected, amendments will realistically need government support to pass, given the large Conservative majority.
Twelve Northern Ireland business organisations are also backing changes to the Brexit legislation.
The organisations met the Northern Ireland political parties in recent days.
Aodhán Connolly, from the NI Retail Consortium, chaired the meeting and described the joint approach of the parties and business groups as "unprecedented".
"Businesses are the lifeblood of our economy and they must be allowed to operate without undue hindrance to ensure they can continue to serve the region, create jobs and support our families," he said.
"That is why we have come together to seek changes to the EU (Withdrawal Agreement) Bill that we believe will protect Northern Ireland's place in the UK internal market and provide the guarantee of equitable and unfettered access to the Great Britain market for both exporters and importers.
"These changes do not seek to undo the will of Parliament in leaving the EU, merely to protect our economy and our households."
https://www.bbc.com/news/uk-northern-ireland-51000560
