I am specifying a complex multivariate model (using this tutorial: https://cran.r-project.org/web/packages/brms/vignettes/brms_multivariate.html). I have computed all the formulas required for the model and saved them as items in list `m1`

. Now I combine them in the model like this:

```
fit1 <- brm(m1[1][[1]]+m1[2][[1]]+m1[3][[1]]+m1[4][[1]], data=df,iter=niter,chains=4,cores=4,family="gaussian",control=list(adapt_delta=0.9))
```

This works great, but the problem is that I would like to do a number of multivariate models in a loop. For this I need to dynamically enter the formulas because each multivariate model has a variable number of formulas. However I can’t find a way to do this - I have tried printing the formula references into strings:

`printedm1 <- purrr::map_chr(c(1:length(m1)),function(x) {if (x==length(m1)){paste0('m1[',x,'][[1]]')`

and then entered the formula references into the model like this:

`fit1 <- brm(cat(sapply(printedm1,function(x) paste0(x)),sep=''), data=df,iter=niter,chains=4,cores=4,family="gaussian",control=list(adapt_delta=0.9))`

but I receive the error `Error in rhs(x)[[2]] : subscript out of bounds`

. Is there a way to enter the formula references dynamically? Thanks I appreciate any advice.