Assuming we're talking UK or EASA...
If you have a current multi-pilot IR issued by the same Authority (eg both UK or both EASA) then to renew or revalidate your single pilot ME IR you only need to complete Section 6 of the test schedule on instruments - EFATO, asymmetric approach to go around, asymmetric circuit to land. There is no problem with doing the ME class rating on the same flight. The reference for cross-crediting is Appendix 8 to Part-FCL.