You should be able to purchase 10% solutions directly from most chemical supply vendors or mix a fresh sample using only a solid as the solute.  You will probably introduce some unwanted variability if you mix and match too much between dilute solution and solutes.

Please check answers to a very similar question at this forum: https://www.researchgate.net/post/How_can_I_make_6_NaOCl_sodium_hypo_chlorite_into_a_30_aqueous_NaOCl_solution12

Either get the salt and prepare the solution by adding 10g of the salt to water to reach 100g final solution, or just boil the water to evaporate about 60 ml out of 100 ml to get a solution has 10% concentration: V4*C4 = V10*C10= 100*4% = 40* 10%.

if you want to go up with concentration to 10%, it means you already have the salt and it would be much easier to prepare the 10%