Is there a way to bound the variances estimates in the `coxme` R package?

Question

I use the variance estimates obtained in a coxmeoutput for a further procedure:

model = coxme(Surv(time, status) ~ (0 + A | B ) + (1| B ) + strata(A) , data)
NUM = sum(unlist(model$vcoef))

However, I need the sum of the two variances estimates (NUM in the example above) to be above 0.01.

Is there any way to add bounds/condition for the variance estimates in the coxme function?

I thought I could do something in the control argument by setting optpar = list(method = "L-BFGS-B", lower=0.005) but I just got errors or strange results.

Thanks in advance for your help!