The denominational St Mirin's High, with just over 300 pupils, and Merksworth High, with fewer than 300, would use the Merksworth site but continue to be run separately.
Renfrewshire councillors cite a precedent in Paisley four years ago when Mossvale and St James' primaries agreed to share the same building.
The authority agreed last week to open informal talks on options for the two secondaries, which serve the deprived Ferguslie and Shortroods communities on the north side of the town.
Brian Oldrey, education chairman, however, insists there will be no repeat of the late 1980s debacle over school reorganisation, which culminated in the notorious Paisley Grammar opt-out ballot and the intervention of then Prime Minister Margaret Thatcher to save the popular school from closure and merger.
Mr Oldrey said: "This is a new style of consultation and we are determined to do this without a predetermined policy. We are beginning with an informal consultation before we go to a statutory consultation. We hope we can pick up other ideas."
But he warned: "We are determined, come what may, that the status quo is not an option. There has to be some significant improvement in the education povided. That is not a criticism of the pupils, parents or teachers but recognition that generations of multiple deprivation drag people down. No matter the final decision, pupils will be in an improved peer group."
Mr Oldrey said the council had learnt the lessons of the former Strathclyde's Adapting to Change approach "where no one thought we were going through a genuine consultation". Current plans will involve extra spending, not cuts, he emphasised.
The council has put forward several options, the most contentious being a joint campus at Merksworth with pupils from St Mirin sharing facilities. It could run as a new community school with enhanced funding or expand by establishing a specialist arts or sports school.
Merksworth is already a centre of excellence for drama and pulls in pupils around Renfrewshire for extra, part-time tuition.
A further option is to close St Mirin's, housed in a dilapidated building, and merge it with the larger St Andrew's Academy, but officials acknowledge that would create extra pressures and leave the north side of Paisley without a Roman Catholic secondary.
The council also recognises it may need to build a new school in another location if it wants community support for its reorganisation plans, although this would need Scottish Executive approval. Gerry McCann