Education Secretary Kirsty Williams wants to increase the Welsh Pupil Premium from Â£300 to Â£600 per eligible child to help raise the attainment of disadvantaged pupils.
Ms Williams is the sole Liberal Democrat in a coalition with Labour.
Meanwhile, Welsh party leader Mark Williams said parties should work together against the Tories.
Ahead of Sunday's speeches in Brighton, the party's sole Welsh MP and leader in the country, Ceredigion's Mark Williams, defended Ms Williams' decision to join the Welsh Labour cabinet in May.
The Ceredigion MP told Sunday Politics Wales the Brecon and Radnorshire AM was taking Liberal Democrat "themes and priorities" into government "very effectively" as education secretary.
He also urged opposition parties to work together against the Tories, saying there was a case for "progressive politicians" to talk about "issues of common interest".
He was left as the only Welsh Liberal Democrat MP after the party's disastrous 2015 general election, with Ms Williams its sole AM after a 2016 assembly poll he said was "arguably worse".
"At this point in time, with boundary changes which massively support and encourage the Conservative Party electorally in the future, I think there is a case for politicians to be talking," he said.
"What I would loosely describe as progressive politicians to be talking about issues of common interest."
Mr Williams said politicians had campaigned across party lines for a Remain vote in June's EU referendum, albeit unsuccessfully.
"There was a positive in the referendum, even for those of us that lost it, in that progressive politicians were working together on a really important issue," he said.
"And I think that dialogue should be extended on other areas of policies as well - otherwise we have the spectre of Conservatism in power in Westminster for a very long time."

The 53-year-old was given the job on a temporary basis in February, following the sacking of Claudio Ranieri.
Shakespeare, who has only worked as caretaker or number two, was Ranieri's assistant after joining the club under former Foxes boss Nigel Pearson.
"This is a really exciting opportunity for me to continue along this new path in my career," said Shakespeare.
"Our preparations for pre-season and the new Premier League campaign have been ongoing for some time, but we can now move on with certainty and ensure we are well equipped to compete at the levels now expected of a club like Leicester City."
Shakespeare won eight of his 16 games in charge last season, leading the club to the Champions League quarter-finals.
As reigning Premier League champions, Leicester were one point above the relegation zone with 13 matches left when Ranieri departed.
But Shakespeare collected 23 points, including wins in all his first five games, to guide the club to 14th place.
Leicester beat Sevilla in the last 16 of Europe's elite club competition, but were knocked out in the next round by Atletico Madrid.
City vice-chairman Aiyawatt Srivaddhanaprabha added: "Craig has shown all the qualities in leadership, motivation and talent management that are required to be successful in this role.
"Those qualities, aligned with his first-class coaching acumen, his knowledge of Leicester City and its philosophy, and the respect he has earned at every level of the club make him the ideal choice to help take us forward."
Plans to double funding for Wales' poorest pupils will be announced at the Liberal Democrat party conference.
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Leicester City have named caretaker boss Craig Shakespeare as their permanent manager on a three-year deal.