customize import wp all import

I am not able to customize the import of products in wp all import , the problem is that my system does not accept the ” – ” in the sku generated by the import… I put the main sku Example: skutest and it generates the skus of the variations as skutest- 1 , skutest-2, skutest-3 and so on… I needed to generate it in o – Example: skutest1 , skutest2, skutest3 because my system does not accept the – in the sku field thank you very much