If you are both, or many and all need a guarantor :
Apply for each person who needs a guarantor and specify that you are in colocation. You'll stand to many on the contract. You can simulate guarantee's price in section price on the website : click here
It is not possible to create a "commun application". Each person who needs a guarantor has to apply.
If you are married :
We act as guarantor for both if you are married. There is a solidarity clause on the lease. That is to say that there is only one person who will pay the fees of the guarantee.