The phrase "altered only by" is correct and usable in written English.
It can be used to indicate that something can be changed or modified exclusively in a specific way or by certain means.
Example: "The terms of the agreement may be altered only by mutual consent of both parties."
Alternatives: "modified solely by" or "changed exclusively by".
Under the proposal, provisions in an enacted law could be altered only by Congressional vote.
but must follow the sequence of the dance, which can be altered only by subtraction.
A spokesman for Representative Anthony D. Weiner, another mayoral hopeful, said by e-mail that Mr. Weiner believed that term limits should be altered only by popular vote.
Employing ancient processes altered only by scientific advancements in some raw materials, "we translate vulnerable clay into a permanent, hard-copy medium, bronze," Mr. Gantz said.
Decouflé's images, because they involve actual human bodies, altered only by costumes, are somewhat less bizarre than Serafini's, but not by much.
The invention of the Hoosier, a cabinet that contained drawers for almost every possible gadget and a work surface in one unit, set a pattern for kitchen design that has been altered only by degree over the decades.
And lo, it has arrived, altered only slightly by the Spinner's hand.
However, the development of treatments that alter only the tissues affected by a particular disease – for example blood cells – is allowed, and clinical trials may start within a couple of years.
It is of considerable significance to ascertain whether new species arise by altering only a few genes or whether the process requires drastic changes a genetic "revolution," as postulated by some evolutionists in the past.
Therefore, our objective is now to hide the traces of the manipulation by altering only the source and destination patches.
In some cases, an existing business model can be rejuvenated by altering only some of its elements.
