Alternate word/phrase for "everything is up for debate"

Is there a synonym to the phrase (if 'synonym phrases' are a thing) "everything will be up for debate" ?

That phrase is commonly used in a collaborative sense, for example - maybe a business owner is creating a new building for his/her company and the design and layout is all open for feedback to the company's existing staff that will soon be moving in. So this owner/boss might say "everything is up for debate" as a way to indicate that everyone can be involved in the design/layout of the new building.

I'm wondering specifically if there isn't a less aggressive; more creative word or phrasing; I feel like 'debate' implies politics but for a creative project like a design or artwork it might be better to say something that gives a 'free and open collaboration' type feeling.

Everything is on the table

Merriam Websters gives this definition under 6.:

— on the table : up for consideration or negotiation

the subject is not on the table

or

Nothing is off-limits

Collins dictionary has this to say about off limits.

phrase
If an area or a place is off limits, you are not allowed to go there.
A one-mile area around the wreck is still off limits.
These establishments are off limits to ordinary citizens.

• Nothing is set in stone yet
• All of the plans are up for discussion
• No plans have been solidified yet
• All of the plans are up in the air
• Nothing has been decided at the moment
• Everything is open for discussion

You can also add onto the sentence to encourage people to give input!

”Nothing is set in stone” is an applicable phrase. It implies that everything is amenable, and any part could be changed as needed.

Once something is set in stone (metaphorically or literally), it cannot be modified or moved easily.

How about ... open for discussion ?

being a subject or issue that people can give their ideas, opinions, etc. about The issue is not open for discussion.

or

... up for negotiation

The important thing to remember is that negotiation is not necessarily adversarial; it often is a strategic process. The objective is to come up with an agreement that benefits all parties. Sometimes parties must give up some things, but this is indeed part of the negotiation, and giving something up frequently allows for gains in other areas of the negotiation.

or

... can be brainstormed

to try to solve a problem or come up with new ideas by having a discussion that includes all members of a group

to discuss a problem or issue and suggest solutions and ideas

Students from Paris, Milan, Tokyo, and New York were invited to the Cambridge campus to brainstorm with MIT students on the marriage of couture and computer.

Engineers are only beginning to brainstorm possible reasons that Polar Lander might have kept silent.

What about "all assumptions will be questioned"?