Can co-signer eventually be able to purchase their own home without me having to refinance?

If my mother co-signs for me and my husband (for us to purchase a starter home that we plan to either sell or rent in 5 years depending on prices, but NOT refinance), would she be able to qualify for a mortgage in 2+ years without counting this house as her debt IF we (my spouse and I) have documented proof that us two alone have been making all monthly mortgage and bill payments on the house? She already owns a house (even with that mortgage on her credit if she co-signs for us it's more than enough for the price home we're looking at), but if she ever wants to upgrade or move to a golf course neighborhood, I don't want her to be held back.

background:
She wants to co-sign for us because even though we earn enough for the house we want, the lender is not considering my husband's second job income (even though it pays more than his main job) because he does not have 2 years with it, only about 7 months (he's very much stable in it and manager is already talking about a promotion).

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