Please also provide the following information in addition to your question:

- Operating System: MacOS High Sierra
- brms Version: 2.5.0

Am trying to execute dyadic growth curve analysis in brms. Specifically, hoping to fit a model like the following that is done in nlme.

```
dyadGC <- lme(Y ~ GENDER + TIME + GENDER*TIME,
data = data,
random = ~ GenderS + GenderS:TIME - 1|dyadid,
correlation = corCompSymm(form = ~1|dyadid/obsid),
weights = varIdent(form = ~1|GenderS),
na.action = na.omit)
```

Where GENDER is contrast coded (-1 and 1) and GenderS is a variable containing strings that indicate “Male” and “Female”. I know that correlation/residual structures are a feature request that is still open, but is there already there a way to fit something similar without the heterogenous compound symmetry correlation structure (e.g., replacing it with the AR(1) structure possibly)?

I have tried the following:

```
formula <- bf(y ~ TIME + GENDER + GENDER*TIME +
(0 + genderS + genderS*TIME | hhid))
m1 <- brm(formula=formula, data=data, chains = 1,
autocor = cor_ar(~ TIME | genderS), cov=TRUE)
```

But this seems to be a slightly different specification. I was hoping someone could offer some advice.