Before an employer can file an I-129 H-1B Visa Petition for a foreign national, the employer must first obtain a certified ETA9035 Labor Condition Application (LCA) from the Department of Labor. If the original company official whose name appears on the LCA is unavailable, the question is whether another company official can sign the LCA in lieu of the originally named official. The answer is "yes". What the company has to do is to have another authorized company official sign the LCA. The new signatory should write their name and title in the relevant fields on page 5 of the LCA and sign where indicated. Don't have them cross out the original signatory's info, just have them write their info next to the original info.
Help this helps.